Hmmmmm...
I honestly can't fully remember what happened. I have a feeling it's one of those EXTREMELY specific bugs where you get to use terminology like "client" and "server", but... all I remember is that as I was going into the hidden area to the left of spawn, I was running into enemies and pushing them without taking damage (also they didn't seem to notice me) and I couldn't collect the double jump after opening the chest.
Maybe my hitbox got hit elsewhere somehow?
Oddly enough, Gary the Scary seemed to know where I was and attacked at me directly. Though, His attacks didn't do any damage.