The 65535 bug can happen to other units. I've had it happen to an allied AI's troopers.
Make sure to read the following slowly. It's convoluted :s :
Did the enemy move one of its hunters to attack a territory that was also sending out attacks to the territory the hunter was on? If the target region's controller the hunters were moving to was sending an attack from that region to the region the hunters were attacking from and was earlier in the rotation, then the hunter's move was cancelled because of that.
It's a behaviour that I've noticed occurs.
