That's exactly the problem with mine; one of the bits inside the cylinder fell apart and jammed the thing up. Instead of spinning freely, mine wasn't able to move freely, and didn't move the pin that engages the actuator inside the door. Of course, I pulled the door panel and the entire lock mechanism to find that out. If I'd known what I was looking for it would've been a matter of pulling the little plastic grommets from the edge of the door, remove the allen screw & pull the lock cylinder out.
(as it was, I got to reassemble everything twice because I forgot to connect the wire harness to the lock & actuator assembly.
good practice I guess.)
The plan now is to check with a locksmith in the morning to see if they can fix it within a reasonable amount of time (less time than it would take to order the repair kit.) If not, I'll just order a cylinder repair kit and do it myself.