Go to expression editor for your logs and use this to see who breaks CC:
Code:fullType=SPELL_AURA_BROKEN_SPELL and targetreaction=REACTION_HOSTILE
SoC can break it if you have MF on. Not sure what else does it. Side note: Does the stun from Axe Toss of a Felguard summoned with GoServ stun an add and then break the CC?