Effect of Copy to reservation

If the string property containing a marking has kept the default Copy to Reservation setting of True, then a user who has Use Marked Objects but does not have the Add Marking permission will not be able to check out a document, even if the user has Full Control of the document itself.

This is by design, since to checkout a document creates a new Reservation document which must have the marking on it due to its property's Copy to Reservation value of True. This requires the marking to be Added to the new document, and since the user in this scenario does not have the Add Marking permission, the checkout will be prevented.