diff --git a/.github/workflows/build.yml b/.github/workflows/build.yml
index 8bff772..33b56d7 100644
--- a/.github/workflows/build.yml
+++ b/.github/workflows/build.yml
@@ -10,15 +10,15 @@ jobs:
     runs-on: ubuntu-20.04
     steps:
     - name: Checkout repository
-      uses: actions/checkout@v2
+      uses: actions/checkout@v4
 
     - name: Setup Node
-      uses: actions/setup-node@v3
+      uses: actions/setup-node@v4
       with:
         node-version-file: '.nvmrc'
 
     - name: Install PHP
-      uses: shivammathur/setup-php@2.7.0
+      uses: shivammathur/setup-php@v2
       with:
         php-version: 7.4
         extensions: mysqli, xmlwriter
@@ -28,13 +28,13 @@ jobs:
     - name: Get Composer Cache Directory
       id: composer-cache-dir
       run: |
-        echo "::set-output name=dir::$(composer config cache-files-dir)"
+        echo "DIR=$(composer config cache-files-dir)" >> $GITHUB_OUTPUT
 
     - name: Cache PHP Dependencies
       id: composer-cache
-      uses: actions/cache@v2
+      uses: actions/cache@v4
       with:
-        path: ${{ steps.composer-cache-dir.outputs.dir }}
+        path: ${{ steps.composer-cache-dir.outputs.DIR }}
         key: ${{ runner.os }}-composer-7.4-${{ hashFiles('composer.lock') }}
 
     - name: Install PHP Dependencies
@@ -43,16 +43,16 @@ jobs:
     - name: Get npm cache directory
       id: npm-cache-dir
       run: |
-        echo "::set-output name=dir::$(npm config get cache)"
-        echo "::set-output name=npm-version::$(npm -v)"
-        echo "::set-output name=node-version::$(node -v)"
+        echo "DIR=$(npm config get cache)" >> $GITHUB_OUTPUT
+        echo "NPM_VERSION=$(npm -v)" >> $GITHUB_OUTPUT
+        echo "NODE_VERSION=$(node -v)" >> $GITHUB_OUTPUT
 
     - name: Cache JS Dependencies
       id: npm-cache
-      uses: actions/cache@v2
+      uses: actions/cache@v4
       with:
-        path: ${{ steps.npm-cache-dir.outputs.dir }}
-        key: ${{ runner.os }}-npm-${{ steps.npm-cache-dir.outputs.node-version }}-${{ steps.npm-cache-dir.outputs.npm-version }}-${{ hashFiles('package-lock.json') }}
+        path: ${{ steps.npm-cache-dir.outputs.DIR }}
+        key: ${{ runner.os }}-npm-${{ steps.npm-cache-dir.outputs.NODE_VERSION }}-${{ steps.npm-cache-dir.outputs.NPM_VERSION }}-${{ hashFiles('package-lock.json') }}
 
     - name: Install JS Dependencies
       run: npm install --legacy-peer-deps
diff --git a/.github/workflows/js-tests.yml b/.github/workflows/js-tests.yml
index b59e752..5fd7330 100644
--- a/.github/workflows/js-tests.yml
+++ b/.github/workflows/js-tests.yml
@@ -14,10 +14,10 @@ jobs:
     runs-on: ubuntu-20.04
     steps:
     - name: Checkout repository
-      uses: actions/checkout@v1
+      uses: actions/checkout@v4
 
     - name: Setup Node
-      uses: actions/setup-node@v3
+      uses: actions/setup-node@v4
       with:
         node-version-file: '.nvmrc'
 
@@ -29,16 +29,16 @@ jobs:
     - name: Get npm cache directory
       id: npm-cache-dir
       run: |
-        echo "::set-output name=dir::$(npm config get cache)"
-        echo "::set-output name=npm-version::$(npm -v)"
-        echo "::set-output name=node-version::$(node-v)"
+        echo "DIR=$(npm config get cache)" >> $GITHUB_OUTPUT
+        echo "NPM_VERSION=$(npm -v)" >> $GITHUB_OUTPUT
+        echo "NODE_VERSION=$(node -v)" >> $GITHUB_OUTPUT
 
     - name: Cache Dependencies
       id: npm-cache
-      uses: actions/cache@v2
+      uses: actions/cache@v4
       with:
-        path: ${{ steps.npm-cache-dir.outputs.dir }}
-        key: ${{ runner.os }}-npm-${{ steps.npm-cache-dir.outputs.node-version }}-${{ steps.npm-cache-dir.outputs.npm-version }}-${{ hashFiles('package-lock.json') }}
+        path: ${{ steps.npm-cache-dir.outputs.DIR }}
+        key: ${{ runner.os }}-npm-${{ steps.npm-cache-dir.outputs.NODE_VERSION }}-${{ steps.npm-cache-dir.outputs.NPM_VERSION }}-${{ hashFiles('package-lock.json') }}
 
     - name: Install Dependencies
       run: npm install --legacy-peer-deps
diff --git a/.github/workflows/php-standards.yml b/.github/workflows/php-standards.yml
index a5fddc4..f9f9f9b 100644
--- a/.github/workflows/php-standards.yml
+++ b/.github/workflows/php-standards.yml
@@ -14,10 +14,10 @@ jobs:
     runs-on: ubuntu-20.04
     steps:
     - name: Checkout repository
-      uses: actions/checkout@v1
+      uses: actions/checkout@v4
 
     - name: Install PHP
-      uses: shivammathur/setup-php@2.7.0
+      uses: shivammathur/setup-php@v2
       with:
         php-version: '7.4'
         coverage: none
@@ -31,13 +31,13 @@ jobs:
     - name: Get Composer Cache Directory
       id: composer-cache-dir
       run: |
-        echo "::set-output name=dir::$(composer config cache-files-dir)"
+        echo "DIR=$(composer config cache-files-dir)" >> $GITHUB_OUTPUT
 
     - name: Cache PHP Dependencies
       id: composer-cache
-      uses: actions/cache@v2
+      uses: actions/cache@v4
       with:
-        path: ${{ steps.composer-cache-dir.outputs.dir }}
+        path: ${{ steps.composer-cache-dir.outputs.DIR }}
         key: ${{ runner.os }}-composer-7.2-${{ hashFiles('composer.lock') }}
 
     - name: Install PHP Dependencies
@@ -45,7 +45,7 @@ jobs:
         composer install --prefer-dist --no-progress --no-suggest --no-interaction
 
     - name: PHPCS cache
-      uses: actions/cache@v2
+      uses: actions/cache@v4
       with:
         path: tests/cache
         key: ${{ runner.os }}-phpcs-7.2-${{ hashFiles('plugin.php') }}
diff --git a/.github/workflows/test-nightly.yml b/.github/workflows/test-nightly.yml
index 114edf0..faaa778 100644
--- a/.github/workflows/test-nightly.yml
+++ b/.github/workflows/test-nightly.yml
@@ -18,10 +18,10 @@ jobs:
     runs-on: ubuntu-20.04
     steps:
     - name: Checkout repository
-      uses: actions/checkout@v1
+      uses: actions/checkout@v4
 
     - name: Install PHP
-      uses: shivammathur/setup-php@2.7.0
+      uses: shivammathur/setup-php@v2
       with:
         php-version: ${{ matrix.php }}
         extensions: mysqli, xmlwriter
@@ -38,19 +38,19 @@ jobs:
     - name: Get Composer Cache Directory
       id: composer-cache-dir
       run: |
-        echo "::set-output name=dir::$(composer config cache-files-dir)"
+        echo "DIR=$(composer config cache-files-dir)" >> $GITHUB_OUTPUT
 
     - name: Cache PHP Dependencies
       id: composer-cache
-      uses: actions/cache@v2
+      uses: actions/cache@v4
       with:
-        path: ${{ steps.composer-cache-dir.outputs.dir }}
+        path: ${{ steps.composer-cache-dir.outputs.DIR }}
         key: ${{ runner.os }}-composer-${{ matrix.php }}-${{ hashFiles('composer.lock') }}
 
     - name: Install PHP Dependencies
       run: |
         composer install --prefer-dist --no-progress --no-suggest --no-interaction --ignore-platform-reqs
-        composer require --dev --update-with-dependencies --prefer-dist roots/wordpress="dev-nightly" wp-phpunit/wp-phpunit="dev-master"
+        composer require --dev --update-with-dependencies --prefer-dist roots/wordpress="dev-main" wp-phpunit/wp-phpunit="dev-master"
 
     - name: Run the tests
       run: |
diff --git a/.github/workflows/test.yml b/.github/workflows/test.yml
index 4f4e9af..0f13dc4 100644
--- a/.github/workflows/test.yml
+++ b/.github/workflows/test.yml
@@ -19,14 +19,14 @@ jobs:
           - '8.2'
           - '8.3'
       fail-fast: false
-    name: WP 6.4 / PHP ${{ matrix.php }}
+    name: WP 6.6 / PHP ${{ matrix.php }}
     runs-on: ubuntu-20.04
     steps:
     - name: Checkout repository
-      uses: actions/checkout@v1
+      uses: actions/checkout@v4
 
     - name: Install PHP
-      uses: shivammathur/setup-php@2.7.0
+      uses: shivammathur/setup-php@v2
       with:
         php-version: ${{ matrix.php }}
         extensions: mysqli, xmlwriter
@@ -43,14 +43,14 @@ jobs:
     - name: Get Composer Cache Directory
       id: composer-cache-dir
       run: |
-        echo "::set-output name=dir::$(composer config cache-files-dir)"
+        echo "DIR=$(composer config cache-files-dir)" >> $GITHUB_OUTPUT
 
     - name: Cache PHP Dependencies
       id: composer-cache
-      uses: actions/cache@v2
+      uses: actions/cache@v4
       with:
         path: ${{ steps.composer-cache-dir.outputs.dir }}
-        key: ${{ runner.os }}-composer-${{ matrix.php }}-${{ hashFiles('composer.lock') }}-wp6.4
+        key: ${{ runner.os }}-composer-${{ matrix.php }}-${{ hashFiles('composer.lock') }}-wp6.6
 
     - name: Install PHP Dependencies
       run: |
diff --git a/README.md b/README.md
index 050a7bb..70e4054 100644
--- a/README.md
+++ b/README.md
@@ -1,6 +1,6 @@
 # Authorship
 
-Stable tag: 0.2.16  
+Stable tag: 0.2.17  
 Requires at least: 5.4  
 Tested up to: 6.2  
 Requires PHP: 7.2  
@@ -61,9 +61,10 @@ _Features without a checkmark are still work in progress._
 ### For development use
 
 * Clone this repo into your plugins directory
-* Install the dependencies:  
+* Ensure you have Composer v2 and Node v16 installed
+* Install the dependencies:
   `composer install && npm install`
-* Start the dev server:  
+* Start the dev server:
   `npm run start`
 
 ## Design Decisions
@@ -133,7 +134,7 @@ This endpoint allows:
 
 ### `authorship` field
 
-This field is added to the endpoint for all suported post types (by default, ones which that have post type support for `author`), for example `wp/v2/posts`. This field is readable and writable and accepts and provides an array of IDs of users attributed to the post.
+This field is added to the endpoint for all supported post types (by default, ones which that have post type support for `author`), for example `wp/v2/posts`. This field is readable and writable and accepts and provides an array of IDs of users attributed to the post.
 
 In addition, user objects are embedded in the `_embedded['wp:authorship']` field in the response if `_embed` is set and the authenticated user can list users.
 
diff --git a/inc/class-insert-post-handler.php b/inc/class-insert-post-handler.php
new file mode 100644
index 0000000..59d9fa9
--- /dev/null
+++ b/inc/class-insert-post-handler.php
@@ -0,0 +1,91 @@
+<?php
+/**
+ * Handler for encapsulating hook callbacks called when inserting posts.
+ *
+ * @package authorship
+ */
+
+declare( strict_types=1 );
+
+namespace Authorship;
+
+use Exception;
+use WP_Post;
+
+/**
+ * Core class for encapsulating hook callbacks called when inserting posts.
+ *
+ * This is needed because state is passed between the callbacks.
+ */
+class InsertPostHandler {
+	/**
+	 * @var array<mixed>
+	 */
+	private $postarr = [];
+
+	/**
+	 * Filters slashed post data just before it is inserted into the database.
+	 *
+	 * @param mixed[] $data                An array of slashed, sanitized, and processed post data.
+	 * @param mixed[] $postarr             An array of sanitized (and slashed) but otherwise unmodified post data.
+	 * @param mixed   $unsanitized_postarr An array (or object that implements array access, like a WP_Post) of
+	 *                                     slashed yet _unsanitized_ and unprocessed post data as originally passed
+	 *                                     to wp_insert_post().
+	 * @return mixed[] An array of slashed, sanitized, and processed post data.
+	 */
+	function filter_wp_insert_post_data( array $data, array $postarr, $unsanitized_postarr ) : array {
+		// Make sure the unsanitized post array is actually an array. Core sometimes passes it as a WP_Post object.
+		$this->postarr = (array) $unsanitized_postarr;
+
+		return $data;
+	}
+
+	/**
+	 * Fires once a post has been saved.
+	 *
+	 * @param int     $post_ID Post ID.
+	 * @param WP_Post $post    Post object.
+	 * @param bool    $update  Whether this is an existing post being updated.
+	 */
+	function action_wp_insert_post( int $post_ID, WP_Post $post, bool $update ) : void {
+		$unsanitized_postarr = $this->postarr;
+
+		$this->postarr = [];
+
+		if ( isset( $unsanitized_postarr['tax_input'] ) && ! empty( $unsanitized_postarr['tax_input'][ TAXONOMY ] ) ) {
+			return;
+		}
+
+		$existing_authors = get_authors( $post );
+
+		if ( $update && ! isset( $unsanitized_postarr[ POSTS_PARAM ] ) && $existing_authors ) {
+			return;
+		}
+
+		if ( isset( $unsanitized_postarr[ POSTS_PARAM ] ) ) {
+			$authors = $unsanitized_postarr[ POSTS_PARAM ];
+		} else {
+			/**
+			 * Set the default authorship author. Defaults to the original post author.
+			 *
+			 * @param array $authors Authors to add to a post on insert if none have been passed. Default to post author.
+			 * @param WP_Post $post Post object.
+			 */
+			$authors = array_filter( apply_filters(
+				'authorship_default_author',
+				[ isset( $unsanitized_postarr['post_author'] ) ? $unsanitized_postarr['post_author'] : null ],
+				$post
+			) );
+		}
+
+		if ( empty( $authors ) ) {
+			return;
+		}
+
+		try {
+			set_authors( $post, wp_parse_id_list( $authors ) );
+		} catch ( Exception $e ) {
+			// Nothing at the moment.
+		}
+	}
+}
diff --git a/inc/cli/class-migrate-command.php b/inc/cli/class-migrate-command.php
index c8d5893..cc86bcc 100644
--- a/inc/cli/class-migrate-command.php
+++ b/inc/cli/class-migrate-command.php
@@ -49,6 +49,12 @@ class Migrate_Command extends WP_CLI_Command {
 	 *   - false
 	 * ---
 	 *
+	 * [--post-type=<post-type>]
+	 * : Post type, or comma separated list of post types.
+	 * ---
+	 * default: post
+	 * ---
+	 *
 	 * ## EXAMPLES
 	 *
 	 *     wp authorship migrate wp-authors --dry-run=true
@@ -79,6 +85,9 @@ public function wp_authors( $args, $assoc_args ) : void {
 			WP_CLI::warning( 'Overwriting of previous Authorship data is set to true.' );
 		}
 
+		$post_types = explode( ',', $assoc_args['post-type'] );
+		WP_CLI::line( sprintf( 'Updating post types: %s', implode( ', ', $post_types ) ) );
+
 		$tax_query = $overwrite ? [] : [
 			[
 				'taxonomy' => 'authorship',
@@ -93,6 +102,7 @@ public function wp_authors( $args, $assoc_args ) : void {
 			$posts = get_posts( [
 				'posts_per_page'      => $posts_per_page,
 				'paged'               => $paged,
+				'post_type'           => $post_types,
 				'post_status'         => 'any',
 				'ignore_sticky_posts' => true,
 				'suppress_filters'    => false,
@@ -249,8 +259,8 @@ function ppa( $args, $assoc_args ) : void {
 				// Usually invalid taxonomy, lets catch and report this.
 				if ( is_wp_error( $ppa_terms ) ) {
 					WP_CLI::error( 'There was an error fetching the PublishPress Author data, is the plugin activated?', false );
-					WP_CLI::error( $ppa_terms );
-					exit;
+					WP_CLI::error( $ppa_terms, false );
+					exit( 1 );
 				}
 
 				/**
@@ -351,9 +361,9 @@ private function get_ppa_user_id( WP_Term $ppa_author, bool $create_users = fals
 		// If this fails we want the debug data, so print out the
 		// arguments so we can reproduce later.
 		if ( is_wp_error( $ppa_user_id ) ) {
-			WP_CLI::error( 'Could not create Authorship user with these arguments:' );
-			WP_CLI::error( $ppa_user_id );
-			return -1;
+			WP_CLI::error( 'Could not create Authorship user with these arguments:', false );
+			WP_CLI::error( $ppa_user_id, false );
+			exit( 1 );
 		}
 
 		return $ppa_user_id;
diff --git a/inc/namespace.php b/inc/namespace.php
index 6699f22..6b5524d 100644
--- a/inc/namespace.php
+++ b/inc/namespace.php
@@ -37,6 +37,8 @@
  * Bootstraps the main actions and filters.
  */
 function bootstrap() : void {
+	$insert_post_handler = new InsertPostHandler();
+
 	// Actions.
 	add_action( 'init', __NAMESPACE__ . '\\init_taxonomy', 99 );
 	add_action( 'init', __NAMESPACE__ . '\\register_roles_and_caps', 1 );
@@ -44,9 +46,10 @@ function bootstrap() : void {
 	add_action( 'enqueue_block_editor_assets', __NAMESPACE__ . '\\enqueue_assets' );
 	add_action( 'pre_get_posts', __NAMESPACE__ . '\\action_pre_get_posts', 9999 );
 	add_action( 'wp', __NAMESPACE__ . '\\action_wp' );
+	add_action( 'wp_insert_post', [ $insert_post_handler, 'action_wp_insert_post' ], 10, 3 );
 
 	// Filters.
-	add_filter( 'wp_insert_post_data', __NAMESPACE__ . '\\filter_wp_insert_post_data', 10, 3 );
+	add_filter( 'wp_insert_post_data', [ $insert_post_handler, 'filter_wp_insert_post_data' ], 10, 3 );
 	add_filter( 'rest_request_after_callbacks', __NAMESPACE__ . '\\filter_rest_request_after_callbacks', 10, 3 );
 	add_filter( 'map_meta_cap', __NAMESPACE__ . '\\filter_map_meta_cap_for_editing', 10, 4 );
 	add_filter( 'user_has_cap', __NAMESPACE__ . '\\filter_user_has_cap', 10, 4 );
@@ -54,6 +57,7 @@ function bootstrap() : void {
 	add_filter( 'the_author', __NAMESPACE__ . '\\filter_the_author_for_rss' );
 	add_filter( 'comment_moderation_recipients', __NAMESPACE__ . '\\filter_comment_moderation_recipients', 10, 2 );
 	add_filter( 'comment_notification_recipients', __NAMESPACE__ . '\\filter_comment_notification_recipients', 10, 2 );
+	add_filter( 'quick_edit_dropdown_authors_args', __NAMESPACE__ . '\\hide_quickedit_authors' );
 }
 
 /**
@@ -330,71 +334,6 @@ function filter_rest_request_after_callbacks( $result, array $handler, WP_REST_R
 	return $result;
 }
 
-/**
- * Filters slashed post data just before it is inserted into the database.
- *
- * @param mixed[] $data                An array of slashed, sanitized, and processed post data.
- * @param mixed[] $postarr             An array of sanitized (and slashed) but otherwise unmodified post data.
- * @param mixed   $unsanitized_postarr An array (or object that implements array access, like a WP_Post) of
- *                                     slashed yet _unsanitized_ and unprocessed post data as originally passed
- *                                     to wp_insert_post().
- * @return mixed[] An array of slashed, sanitized, and processed post data.
- */
-function filter_wp_insert_post_data( array $data, array $postarr, $unsanitized_postarr ) : array {
-
-	// Make sure the unsanitized post array is actually an array. Core sometimes passes it as a WP_Post object.
-	if ( ! is_array( $unsanitized_postarr ) ) {
-		$unsanitized_postarr = (array) $unsanitized_postarr;
-	}
-
-	/**
-	 * Fires once a post has been saved.
-	 *
-	 * @param int     $post_ID Post ID.
-	 * @param WP_Post $post    Post object.
-	 * @param bool    $update  Whether this is an existing post being updated.
-	 */
-	add_action( 'wp_insert_post', function( int $post_ID, WP_Post $post, bool $update ) use ( $unsanitized_postarr ) : void {
-		if ( isset( $unsanitized_postarr['tax_input'] ) && ! empty( $unsanitized_postarr['tax_input'][ TAXONOMY ] ) ) {
-			return;
-		}
-
-		$existing_authors = get_authors( $post );
-
-		if ( $update && ! isset( $unsanitized_postarr[ POSTS_PARAM ] ) && $existing_authors ) {
-			return;
-		}
-
-		if ( isset( $unsanitized_postarr[ POSTS_PARAM ] ) ) {
-			$authors = $unsanitized_postarr[ POSTS_PARAM ];
-		} else {
-			/**
-			 * Set the default authorship author. Defaults to the orignal post author.
-			 *
-			 * @param array $authors Authors to add to a post on insert if none have been passed. Default to post author.
-			 * @param WP_Post $post Post object.
-			 */
-			$authors = array_filter( apply_filters(
-				'authorship_default_author',
-				[ isset( $unsanitized_postarr['post_author'] ) ? $unsanitized_postarr['post_author'] : null ],
-				$post
-			) );
-		}
-
-		if ( empty( $authors ) ) {
-			return;
-		}
-
-		try {
-			set_authors( $post, wp_parse_id_list( $authors ) );
-		} catch ( Exception $e ) {
-			// Nothing at the moment.
-		}
-	}, 10, 3 );
-
-	return $data;
-}
-
 /**
  * Adds the authorship field to the REST API for post objects.
  *
@@ -814,3 +753,18 @@ function filter_comment_notification_recipients( array $emails, int $comment_id
 
 	return array_unique( array_merge( $emails, $additional_emails ) );
 }
+
+/**
+ * Hide author select from quick edit.
+ *
+ * Bit of a hack, but filter filter_quickedit_authors and include only author with ID 0.
+ * Also hide if only one author just in case someone someone has created author with 0.
+ *
+ * @param array $options Options.
+ * @return array Options.
+ */
+function hide_quickedit_authors( array $options ) : array {
+	$users_opt['hide_if_only_one_author'] = true;
+	$users_opt['include'] = [ 0 ];
+	return $users_opt;
+}
diff --git a/package-lock.json b/package-lock.json
index e6f93e8..7fcb779 100644
--- a/package-lock.json
+++ b/package-lock.json
@@ -1,12 +1,12 @@
 {
   "name": "@humanmade/authorship",
-  "version": "0.2.16",
+  "version": "0.2.17",
   "lockfileVersion": 2,
   "requires": true,
   "packages": {
     "": {
       "name": "@humanmade/authorship",
-      "version": "0.2.14",
+      "version": "0.2.17",
       "license": "GPL-3.0-or-later",
       "dependencies": {
         "@types/react-select": "^3.0.26",
diff --git a/package.json b/package.json
index 32566c4..a99b5f3 100644
--- a/package.json
+++ b/package.json
@@ -1,6 +1,6 @@
 {
   "name": "@humanmade/authorship",
-  "version": "0.2.16",
+  "version": "0.2.17",
   "description": "Authorship",
   "private": true,
   "main": "src/index.tsx",
@@ -9,12 +9,15 @@
     "lint": "concurrently -n CSS,JS -c cyan.bold,yellow.bold \"npm run lint:css\" \"npm run lint:js\"",
     "lint:css": "stylelint src/",
     "lint:js": "eslint --ext .js,.jsx,.ts,.tsx src/",
-    "start": "webpack-dev-server --config=.config/webpack.config.dev.js",
+    "start": "webpack serve --config=.config/webpack.config.dev.js",
     "build": "webpack --config=.config/webpack.config.prod.js",
     "bump:patch": "bump patch --commit 'The v%s release' package.json package-lock.json README.md plugin.php",
     "bump:minor": "bump minor --commit 'The v%s release' package.json package-lock.json README.md plugin.php",
     "bump:major": "bump major --commit 'The v%s release' package.json package-lock.json README.md plugin.php"
   },
+  "engines": {
+    "node": "16"
+  },
   "dependencies": {
     "@types/react-select": "^3.0.26",
     "@wordpress/editor": "^9.24.3",
diff --git a/plugin.php b/plugin.php
index 4369d15..088fd1f 100644
--- a/plugin.php
+++ b/plugin.php
@@ -9,7 +9,7 @@
  *
  * Plugin Name:  Authorship
  * Description:  Authorship plugin for WordPress.
- * Version:      0.2.16
+ * Version:      0.2.17
  * Plugin URI:   https://github.com/humanmade/authorship
  * Author:       Human Made, initially funded by Siemens.
  * Author URI:   https://humanmade.com/
@@ -43,6 +43,7 @@
 require_once __DIR__ . '/inc/namespace.php';
 require_once __DIR__ . '/inc/taxonomy.php';
 require_once __DIR__ . '/inc/class-users-controller.php';
+require_once __DIR__ . '/inc/class-insert-post-handler.php';
 require_once __DIR__ . '/inc/template.php';
 
 if ( is_admin() ) {
diff --git a/src/components/AuthorsSelect.tsx b/src/components/AuthorsSelect.tsx
index 5c90ae7..071d600 100644
--- a/src/components/AuthorsSelect.tsx
+++ b/src/components/AuthorsSelect.tsx
@@ -58,7 +58,7 @@ const AuthorsSelect = ( props: AuthorsSelectProps ): ReactElement => {
 
 	if ( ! selected.length && isEqual( preloadedAuthorIDs, currentAuthorIDs ) ) {
 		setSelected( preloadedAuthorOptions.authors );
-	} else if ( currentAuthorIDs.length && ! selected.length ) {
+	} else if ( currentAuthorIDs !== undefined && currentAuthorIDs.length && ! selected.length ) {
 
 		const path = addQueryArgs(
 			'/authorship/v1/users/',
diff --git a/tests/phpunit/test-cli.php b/tests/phpunit/test-cli.php
new file mode 100644
index 0000000..42f7392
--- /dev/null
+++ b/tests/phpunit/test-cli.php
@@ -0,0 +1,78 @@
+<?php
+/**
+ * Plugin CLI command tests.
+ *
+ * @package authorship
+ */
+
+declare( strict_types=1 );
+
+namespace Authorship\Tests;
+
+use Authorship\CLI;
+use const Authorship\POSTS_PARAM;
+use const Authorship\TAXONOMY;
+
+class TestCLI extends TestCase {
+	public function set_up() {
+		parent::set_up();
+		require_once dirname( __DIR__, 2 ) . '/inc/cli/namespace.php';
+		require_once dirname( __DIR__, 2 ) . '/inc/cli/class-migrate-command.php';
+		CLI\bootstrap();
+	}
+
+	public function testMigratePostTypePost() : void {
+		$factory = self::factory()->post;
+
+		// Post. Owned by editor, attributed to nobody.
+		$post1 = $factory->create_and_get( [
+			'post_author' => self::$users['editor']->ID,
+		] );
+
+		// Unset author data.
+		wp_set_post_terms( $post1->ID, [], TAXONOMY );
+
+		// Check initial authorship data unset.
+		$authorship_authors = \Authorship\get_authors( $post1 );
+		$this->assertCount( 0, $authorship_authors );
+
+		$command = new CLI\Migrate_Command;
+		$command->wp_authors( [], [
+			'dry-run' => false,
+			'post-type' => 'post', // Note, have to set default values manually.
+		] );
+
+		// Check migration command has correctly set the author.
+		$authorship_authors = \Authorship\get_authors( $post1 );
+		$this->assertCount( 1, $authorship_authors );
+		$this->assertSame( self::$users['editor']->ID, $authorship_authors[0]->ID );
+	}
+
+	public function testMigratePostTypePage() : void {
+		$factory = self::factory()->post;
+
+		// Page. Owned by editor, attributed to nobody.
+		$page1 = $factory->create_and_get( [
+			'post_author' => self::$users['editor']->ID,
+			'post_type' => 'page',
+		] );
+
+		// Unset author data.
+		wp_set_post_terms( $page1->ID, [], TAXONOMY );
+
+		// Check initial authorship data unset.
+		$authorship_authors = \Authorship\get_authors( $page1 );
+		$this->assertCount( 0, $authorship_authors );
+
+		$command = new CLI\Migrate_Command();
+		$command->wp_authors( [], [
+			'dry-run' => false,
+			'post-type' => 'post,page',
+		] );
+
+		// Check migration command has correctly set the author.
+		$authorship_authors = \Authorship\get_authors( $page1 );
+		$this->assertCount( 1, $authorship_authors );
+		$this->assertSame( self::$users['editor']->ID, $authorship_authors[0]->ID );
+	}
+}
diff --git a/tests/phpunit/test-post-saving.php b/tests/phpunit/test-post-saving.php
index 069e242..db82d27 100644
--- a/tests/phpunit/test-post-saving.php
+++ b/tests/phpunit/test-post-saving.php
@@ -137,4 +137,20 @@ public function testPostAuthorshipIsSetToEmptyWhenUpdatingPostWithNoExistingAuth
 
 		remove_filter( 'authorship_default_author', '__return_empty_array' );
 	}
+
+	public function testMultiplePostInsertionDoesNotCompoundActions() : void {
+		global $wp_filter;
+
+		$before = count( $wp_filter['wp_insert_post']->callbacks );
+
+		for ( $i = 0; $i < 3; $i++ ) {
+			wp_insert_post( [
+				'post_title' => "Testing $i",
+			] );
+		}
+
+		$after = count( $wp_filter['wp_insert_post']->callbacks );
+
+		$this->assertSame( $before, $after );
+	}
 }