Pretty much all cases of this that I’ve seen can be traced back to a mismatch between the AlbumArtist meta tag and the storage location of the album with that meta tag in a wrong Artist folder.
Even a single wrong (or missing) album artist tag can poison all albums which are stored inside the same artist folder.
This can even continue to affect your library if you have rectified the above mismatch afterwards.
You still may have to Plex dance all involved album artists and their respective albums.
Not in my experience, not at all.
