[General] Stuns vs mobs

[Grazzia]

WoW Freakz link: -

Bug description: So when a mobs are stunned(so the debuff persent on the given mob, saying stunned) it shouldnt be able to cast/melee attack/move anywhere yet on freakz it happens really often that mobs simplely continue everything as if nothing happened. This has nothing to do with the fact that stunning a mob multiple times can cause it to became immune because it may happen on first stun too.
I am writing about this now without raging affix(well-known old bug that raging affix makes mobs immune to almost all kind of cc).

Proof: https://imgur.com/a/k4a04sx
-In CoS the mob was stunned with mighty bash, yet it casted quelling strike without any shame
-In NL that pelter was stunned with mighty bash and later another one with chaos strike too, both was uneffective, it casted at least 3 jagged disk while it was stunned

It is not only these two but happens in general for example in arcway on the withered manafinds when they cast siphon. I couldnt find whats the difference when stun works and when its uneffective so it seems random so far.