How Does AI Directly Attack My Stealthed Toons?

I've had this happen to me on the higher speed settings. It was suggested that maybe an assist attack with an initial crit caused the stealth and the second attack appeared to go directly at a stealthed character. I'm like you and swore up and down that the toon was in stealth prior to the attacks and that kylo obviously couldn't have been but I'd never been able to catch a recording of it so it was kinda swept under the rug.