Apple Music Only Shows Partial Library After Importing New Album

Got a new M3 Max Macbook Pro about two weeks ago. We had to finally switch over from iTunes to Music since Retroactive doesn't work on Sonoma yet. It took about three days for Music to get all the artwork into the library properly. It's a gigantic collection of over 1.2M songs. There are some small differences we're trying to adjust to that are different from iTunes, but it mostly seems fine.

Yesterday we tried importing some new music into Music. It took about 40 mins for the first album, which seemed incredibly long. Then the library and playlists all went from normal to only showing artists from A-M. Any artists that are N-Z were gone from the program. The bottom of Music shows that there are still 1.2M songs, but it will only scroll to somewhere in the "M" artists.

Any ideas on what the heck is going on? If we restart Music then the full library shows again, including whatever was imported.

We don't use iCloud Sync and never have. The library is close to 11TB and has unreleased music, so storing it in the cloud is not going to happen. We also do not and won't use Apple Music streaming, so suggestions involving those are not going to be helpful.