So... Five months later, I still have not been able to fix the game. I attached some gifs of the problems in action, and you can probably tell why I deem the game "unplayable" until it's fixed. 

So what's going on? In short: The camera won't move. As far as the debug console is concerned, the camera IS moving. However, the gameplay says otherwise. The parallax backgrounds and cave light effects move relative to the camera's position, so you can tell that the game is recognizing the camera's position, but the screen just won't budge... 

There are a few other problems, such as the game crashing whenever I try to start a level's music. I have zero idea how a GameMaker runtime update broke all this when none of it relates to their change notes. It also messed up some of my side projects at the time to the same effect (broken camera, music problems).

I've tried nearly everything, I'm exhausted and tired of this problem, but I haven't given up just yet. I've been working on some other game projects in the meantime, which I hope to have released in some form of early access around summertime (I can't make any promises though).

Thank you for your patience.

- Adam "PixelDough" Worrell