Refresh/rescan doesn't work:
1. Open contact sheet.
2. Delete one or more files.
3. Open Trash in Finder.
4. Drop just deleted files back on contact sheet to undo the delete.
5. Contact sheet doesn't show dropped files, performing refresh or rescan doesn't make them appear either. You need to close and reopen contact sheet to get all files again.
Required outcome: after step 4, the contact should be updated and show all files (immediately).
Note: it seems it only doesn't work for files files deleted from within PM which are then retrieved from the trash.
Mac OS X 10.14.5 PM6 3331 / PM+ 3328