I just had a fight with Satele against Cassian. After about two minutes the two allies (Vel and Cinta) were gone. Then I threw the battle on auto. For the entire rest of the battle, there wasn't a single critical hit.
I checked the stats afterwards. The Cassian did not have any Crit Avoidance (0% in both Physical and Special). He only gains Crit Avoidance from Undermined enemies, which my guys never were. That only comes from him using abilities (he was always stunned), my guys dispelling his buffs (he always had buff immunity) or 3 out of turn attacks in one of my turns (impossible because there are only 2 allies to attack out of turn). The Cassian team does not have any way to reduce Crit Chance on enemies AFAIK. The team did not have a datacron.
This seems bugged, and caused me to drop a battle. Then again, I have been known to be quite stupid, so maybe I missed something, in which case please enlighten me (unironically).