In combat, when an opponent starts a heavy attack, I'm supposed to be able to launch a fast counterattack that interrupts my opponent's attack. Unfortunately, it feels like the interrupt often doesn't work. I'll hear the windup, strike the opponent, hear my strike hit, and then still get hit myself. It's frustrating. Is this a timing issue? Am I doing the interrupt too late to actually stop the attack? Any ideas on what I'm missing here?