Hi Kirk
Yes, indeed all the images can be copied by finder, once the card has been remounted and it is fine and shows as a normal file. However, when I navigate to the file in question while still mounted at the end of the PM ingest process, the file shows with a generic DNG style thumbnail, which suggested it is in some way different from all the other CR2's. Very predictable and repeatable, only showing when using PM ingest (very strange an new). The cards are 1-3 years old, I would not think they are anywhere near the end of their useful life, all top quality 'single level' cards.
Thanks
Graham