So when I stumble an enemy with a dual casted destruction spell via the Impact perk they cannot be hit with spells until they are almost fully recovered. The spells seem to travel right through them even when the reticle is centered on their crouched body. Spells do sometimes hit, but rarely. This is my first spell caster so I was wondering if this mechanic/bug has been in the game since the get go or if one of the three DLC (of which I have all 3) introduced it. Also wondering if it is a bug or just a mechanic. Also worth noting that I'm playing on an xbox.