UPDATE: Finally solved. I realized the graphics settings had reset for some reason. I guess the slider on Graphics > Definition removes some map features when set to the "High Performance."

So for anyone else having this issue, set it (again, that's Graphics > Definition) to anything except "High Performance;" all other options have the player/enemy icons.

Not even sure why this is an option. It's a 2D sidescroller game; everything should be relatively high performance. I've never dropped below the 165 FPS cap I set.