THIS IS THE SOLUTION!
Apple is using a new library format ".musiclibrary", you can find it in the new Music folder named "Music Library.musiclibrary". You can ask it to rebuild the library by ,quit Music, after press option key + click to start without a library. Then select Choose Library and select from iTunes folder the file named "iTunes Library.itl". Then Music asks for a location to store the new library, which will be in Music/music. Then Music should start loading artworks (just allow some time depending on the size of library).
All the best!
Hope for better OS updates from apple next time!
I feel like apple start to go down...