The buckle doesn't unlatch until you are sitting upright. Also, the harnesses do lock. Sure, the move around a little, but that's so you can breath. Next time you go on, buckle the restraints, and push up on the harness...they will move. Then, when the ride ops come by and push down on the shoulder harnesses, push up again...they will be locked.
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KoЯn Rules! I just came out to feed!