Photo Mechanic on Mac has a problem copying locked files to a CIFS/SMB share (and I suspect an exFat-formatted external) because of the way the copy operation is performed. The actual problem is that PM copies the file to the drive (as a .tmp_<string>.<ext> file) and then tries to rename it, but the name change fails because the file is locked making it read only. It needs to change so that it: detects a locked file, unlocks it, copies it, renames it, and re-locks it. Alternatively/additionally, I propose an option to "unlock all files as they're copied", that will KEEP them unlocked (so you can actually do something with them afterward).
This is relevant because many cameras' locking operations actually do lock the file as read-only (a common procedure to chimp in camera by locking the ones you want and then erasing all the unlocked images).
Tested on Photo Mechanic 5 rev. 17146
