Bosses in bugged state

Now that I am hitting harder, I have had several instances where I am fighting doryani in citadel and I put him into bleed and heavy stun down to 50% life where he starts mitigating everything because he is supposed to go into phase 2 of the fight; however he is recovering from heavy stun and going into chained back to back attack animations and due to his damage mitigation to go into phase 2, i lack leech and end up dying. not sure if this is intended but i have better luck putting him into phase 2 if i dont use my build and just spear throw and take him down slower.

Anyone else experience this?