Cannot use Power Punch, cannot smash through the red door to progress

[Practice Makes Perfect XD]

Can't do that move at 12:44 from this video for some reason

https://www.youtube.com/watch?v=xfAm-2dP730&list=PLMXrUq2Gpxr8uzwkaJS9xRc54HUp0uAj5&index=3

I try to hold the Light Attack button (Fist is already equipped because it's the only weapon I have, right?)

What am I missing? Any help would be appreciated
Is this a bug or am I doing it wrong?