I've noticed that while using camouflaged hunter / bow (first shot from stealth) , the damage is greater when firing the first shot, then waiting to watch the health bar decrease vs firing the first shot and immediately activating another skill. I've tested this against all types of daedra (they are the only guaranteed proc)

It is weird, idk why this is happening. Does heavy attack damage lower when activating another ability mid flight? Is it a camo hunter bug? The distinct proc sound happens either way, bit since I am playing on Xbox one, there is no way to see actual damages numbers. Help? Suggestions?