Okay, so I was on volskya and 3 times I targeted our blaze to heal him. And 3 times ancestral would go off. I would get the full cooldown and yet he would heal for maybe 10 HP like his HP bar would barely go up. I used it on out azmodan and his HP bar went all the way up. So there’s something about blaze and ancestral that’s causing it to not heal. And no there was no stuns or anything involved.
Try and see if the same happens when you use Alexstraza’s Life-Binder on Blaze under similar conditions
Might help narrow the issue down
Were there anti-heals in play? For example Ana’s antiheal grenade?