Keep in mind, other effects can cause disengages that Paralytic Aura would prevent. Anything that allowed a model to move after a strike, like the Wolves normal attack, or the Pelegarth Howl's training that would let someone move if an ally gets disengaged from, would not be allowed by Paralytic Aura. Basically, once you are engaged, you are stuck unless they disengage you, your you do something to force them away, like knockback.