I had the same problem, which was solved using “last.fm agent” instead of “plex music agent”, do some testing and you will see.
You need to FOLLOW these steps:
- Go to the advanced settings of your music library
- Select the LAST.FM agent
Note 1. All your songs must have the album title.
Note 2. If you only have two or more songs from the same album, you must put the track number in each song.
Done.
You will see your library the way you want it!
I hope you find it useful