Hitch will not come off the ball.

This should not be a regular event. Try watching the shaft from the hitch head to the receiver. You should notice a point when the weight is off the truck but before it starts lifting it. Lift the ball lock at that point, a couple of cranks later the tongue should be high enough that the lock will not engage. Somehow you are getting the lock into a bind. If you are unhooking on some sort of incline, chock the trailer wheels before you start, put the truck in neutral and it will probably move very slightly to a straighter alignment and release the bind. If you are pointed down hill, you may have to put it in reverse for a second.