Ah that’s strange, they should be picked up as long as they are in the music folder. Do you mind sharing the format of one of the songs that isn’t recognized?
If you have time, could you open the app from the terminal (flatpak run io.github.mmarco94.tambourine) and see if any interesting log pops up?
Thanks! Honestly, that’s really out of scope for this project. Maybe you could mount the folder with your music locally, although I can already tell you it’s gonna be pretty slow if you have a medium/large music library.
Have you looked into Plex Amp? I’ve been told it’s decent.