Garageband won't save

I've been using GB for about 8 years now and never had this issue. Just yesterday, it stopped letting me save projects and started giving me this error:

"The file (insert track file name)” couldn’t be opened.

I'm zealous about saving every time I edit a song, and tried backing up several versions, but still get the same error no matter what.

I loaded another song I'm working on to verify it wasn't a glitch with the current song, and get the same error message.

Currently running GB version 10.4.6 and OS Monteray 12.6