I never had this problem, neither with versions before 3.12 nor with 3.12.
But you could try version 3.12a. There was another problem with handling duplicates during copy and move which was fixed in version 3.12a. Copy and Move have been reimplemented programmatically since this version. Maybe it helps with your problem.
FIX: copying or moving files resulted in inconsistent display of data if overwrite or keep both is used. (#56008)