I'm having the same issues—quite randomly and suddenly. The thing I noticed is that it began happening after I did the following:
1. Finish artwork with multiple art boards.
2. Go to Export Persona. I see that the slices' names are not the same as the art boards, which I renamed earlier.
3. Under "Slices", I select and delete all slices (except background).
4. Under "Layers", I select all artboards and click "create slice", thereby updating all slices to the correct names.
5. I set export parameters for the slices, and click "Export Slices" 6. App freezes as soon as the "Select folder" window opens up.
7. I force quit app. Restart app doesn't always work. Restarting my computer usually works, but freezing may occur again, always at the same spot—the "Select folder" window.
I'm on Mac OS Monterey, ver. 12.2.1, but the issue started happening shortly before the update. I updated my Mac hoping the issue would go away.