The deadbolt on Pete, our 2014 FC 27FB got to "sticking" in the unlocked position in January. The retracted "bolt" portion would hang up on the bracket and get stuck inside the door. Luckily it only stuck unlocked. I could take a small screwdriver and help the bolt past the bracket and it would work. Perhaps yours is doing the same thing? I filed the rough edges on the bolt a bit and then the dealer lubricated and adjusted it in March during a week long "warranty punch list" visit. So far, it has worked perfectly ever since.
The thing I like about the deadbolt is that it is more "substantial" than the keylock on the handle assembly. At least I think it is. It just seems to better handle the repeated use than the "little" lock. Plus, I can't lock myself out of the trailer as easily. (you can lock the flipper handle or use the little key on purpose or by accident, close the door, and guess what?) Our 3yo grandson locked himself inside Pete when it was ours for like 10 days last November
by accidentally flipping the little handle on the small lock. That was a trip as I had the spare keys 30 miles away. NOW we have spare keys accessible at all times!