[jimcol]

Had a fellow camper have a similar experience as the OP. Several of us trying to help thought the key wasn't unlocking. After much debate and entry attempts decided the lock was unlocked but the latch was bound in the strike plate. Leaning in on the door with a shoulder in the vicinity of the latch while pulling the handle open with the claws of a hammer opened the door. Cleaned the latch real good and applied a coat of silicone dry lube and it worked like a champ. Since it was already happy hour, we suggested to the owner to take a file and slightly enlarge the hole in the strike plate.