Well its not a bug, it looks like I played it wrong the whole time. :D What I did was holding up the shield, thinking perhaps it would "charge" it, and then I would sidestep the enemy and "push them" from the side. That worked sometimes (I guess when I bumped unknowingly into walls, or maybe I did sometimes stun them correctly while blocking). I still managed to keep a balanced duality ratio for the game until the last fight, haha.