About two month ago following problem occured and I haven't been able to fix it since:
I saved albums into "albums" and downloaded them there for years.
They were just there and I didn't save them some where else as individual playlists.
Then, I don't know if it happened after an update, all my saved albums were gone and in "albums" the albums to every song I ever saved under "songs" showed up. But with only the songs of the album I saved under "songs" of each album.
When I save a album now, all the songs of the album are just saved into "songs"....
It's a big mess 😄
Btw, jusing Spotify Family/Premium on Android and Windows.