After updating to 2.4.0, I was hit with the same issue as #216. I cleared user data, but when I tried to re-add my library, I found that the directory picker does not show any directory outside /storage/emulated/0/Music.
I reverted to 2.3.3. It does not have this problem, the directory picker shows entire internal storage.
I checked app permissions, and I could not add or expand any to 2.4.0. Version 2.3.3 seems to be using a different permission for accessing filesystem.
I'm on Android 13.
As a suggestion: I'm not familiar with Android development, but I've seen other apps use some other form of granting access to certain directories, that integrates with the system file picker and does not require the app to be able to browse the filesystem by itself. Perhaps this is what AudioAnchor should be doing, instead of using the audio files permission.