Similar issue to # Cannot access file XYZ via secure bookmark
I recently upgraded to Mac OS Sonoma & this issue which was resolved is back and the fixes don't seem to work
Can you try this command via Terminal.app while Mp3tag being closed:
defaults delete app.mp3tag.Mp3tag SecurityScopedBookmarks
After that, load the folder (not the individual files) via ⌘O and see if the issue persists.
If the issue persists, I’d need more details about the concrete actions you’re performing that trigger the error and ideally a screenshot of the error message.