Attack Timer Triggered Bug

I've attached an image showing the bug. I should not have an attack timer here, only the enemy, as my units were stationary and in a fort when they were attacked.

I was bombarding enemy artillery with my artillery, and then I split my stack when the enemy tanks charged. My artillery retreated, but I left anti-tanks in the fort. When the enemy tanks attacked, my troops re-upped their attack timer from the earlier artillery barrage even though they were stationary (and the stack in the fort has no artillery in it). You can see that the attack timer says "Attacking Anau," which is where the enemy artillery are stationed. I will likely lose this very pivotal and close battle that would have otherwise been won apart from this bug.

This should not happen, stationary units should never have an attack timer unless given a move, attack or stop command (which I did not do here).