The perma stun is meant to be like that, its a channel. A simple interrupt or stun from a party member on the mob will break it.
No I mean, Out of combat - mob is dead, I am stunned.
It shows im still in combat in that one, but it persisted through combat, when the specific mob was dead and until I used my anti-cc ability.
Also once I had used that it left a debuff (constricted) on there which was not even working properly anyway as shown below
Not to mention the 3x (strong not elite) adds on the bonus boss with 32-36k health each. Was worried we wouldn't do it in time but didn't seem to be a problem.