Step 3's "Mix in Studs From Existing Set" -> "Import From File" doesn't automatically process to go to Step 4

[b321gonzo]

Using Google Chrome on Windows 10.
If on step 3, I clear available pieces, and then go to import from file under the mix in studs from existing set option, it doesn't automatically update to process to go to step 4. After importing the file it will still show available pieces as "0" and doesn't update unless I manually change one of the quantities of a color I imported in.