Cannot add tracks to playlist

[jaedb]

I can create a Playlist successfully 🎉 however when attempting to add tracks, it appears to work, but the server logs suggest otherwise. Refetching said playlist confirms that the tracks were not actually added to the remote asset.

These requests are send to the Mopidy JSON-RPC API (ie POST http://mopidy-server:6680/mopidy/rpc).

Playlist create request

{
	"method": "core.playlists.create",
	"params": {
		"name": "My rad playlist"
	},
	"jsonrpc": "2.0",
	"id": 1
}

Add tracks request

{
	"method": "core.playlists.save",
	"params": {
		"playlist": {
			"__model__": "Playlist",
			"uri": "XXX (RESULT FROM PREVIOUS REQUEST HERE)",
			"name": "My rad playlist",
			"tracks": [
				{
					"__model__": "Track",
					"uri": "ytmusic:track:dEp_vC1La_s"
				}
			]
		}
	},
	"jsonrpc": "2.0",
	"id": 1
}

Server log

ERROR    2022-12-03 09:31:00,201 [7:YTMusicBackend-3] mopidy_ytmusic
  YTMusic failed adding items to playlist
Traceback (most recent call last):
  File "/var/lib/mopidy/.local/lib/python3.7/site-packages/mopidy_ytmusic/playlist.py", line 115, in save
    self.backend.api.add_playlist_items(bId, list(add))
  File "/var/lib/mopidy/.local/lib/python3.7/site-packages/ytmusicapi/mixins/playlists.py", line 280, in add_playlist_items
    response = self._send_request(endpoint, body)
  File "/var/lib/mopidy/.local/lib/python3.7/site-packages/ytmusicapi/ytmusic.py", line 144, in _send_request
    raise Exception(message + error)
Exception: Server returned HTTP 400: Bad Request.
Request contains an invalid argument.