Invincible after one hit.

[withered]

I read that high FPS causes this glitch, fair enough, but my problem is there's no in game way to cap the FPS. In windowed it runs at 60FPS and I am able to take damage properly but in fullscreen it runs at 1200+FPS and my invincible frames last forever. I don't even know if the game is meant to be run at 60 or 30 FPS by default?