Album artwork missing after iTunes -> Music conversion

After changing my iTunes Library from iTunes to the new Music app on Big Sur many of my music files are missing album artwork inside the new Music app:

Music App missing covers

The thing that’s worth nothing is that album artwork was embedded inside the .m4a files. There’s a thumbnail of the image near the controls on music app, but it does not show as a big image on the application itself.

If I fire up the “mini player”, the cover appears on top but not on individual files:

Miniplayer

Finally if we get to the filesystem itself, Finder is able to load and show the covers in individual files, observe the icons near the filename.

Files in Finder

If we look at additional information from Finder shows the artwork correctly too, and as you can see I’ve the file since 2011:

More info on Finder

Last but not least, there’s the “more info” directly on the Music.app missing the cover:

Missing cover in more info Music.app

I even checked the tags on other software, in my case I just used Foobar2000 to check for metadata and foobar2000 detected everything as it should:

foobar2000 Details
foobar2000 Artwork

So at the end my years-organized collection just lost almost 50% of the covers and is looking like some unorganized iTunes installation from the no tag MP3 era, the 90’s:

Sad music collection

Any ideia of what may have happened and any idea on how to automate and fix this?

Thanks.

PS: I’m aware of the amusing dougscripts.com but now it’s payware and I’m not sure if the scripts would solve the issue or not, it seems that even with the scripts it’s a lot of manual work to fix my entire collection because something broke with Music.app.