I mind controlled an arthron during an ambush. Exited all my characters. The arthron remained controlled after the priest left. The pandorans won’t kill it. So the scenario just went on endlessly.
Eventually I tried suicide: the arthron manage to give itself a bleed wound with blaster arm grenades. But still 19 turns of watching many enemies wander around aimlessly. Not fun.
Ouch that sucks!
I got one for ya. I had my Tech Turrets MURDER two of my soldiers that were controlled by mindfraggers. Nothing I could do, they controlled my people, and at the end of the enemy turn the turrets gunned them down. 
So many bugs, so many reloads.
That would be terrible. I hate losing soldiers. If my guy is mind controlled, I have my techs pick up the turrets. They are very powerful and I didn’t want to take a chance. Or I didn’t lay them down if any were mind controlled. Just a thought.