Kelleran unkillable?

Is there a Kelleran Beq glitch to make his team unkillable?  In Conquest sector 2 I had his whole team down to red bar health with no protection yet not one would go down.  I didn’t see anything online to explain why or how to get around this.  What am I missing? 
-was using pirates (CI, Vane, Brutus, Hondo, PCH)