yea i was using orthogonal. I tried with the perspective camera and kept fighting against the player disappearing when walking left. This was an experiment to get a feel of paper 2d and paper zd systems and i had a lot of fun with this project. Only wished the camera was better because it was really hard to design nice looking levels because of it. I feel i was able to get everything down to a respectable size. The exe was down to only 500mb which is pretty good for an unreal engine game.
Best guess is you needed a 2 sided poly - your normals were pointing out on right side, and in (disappearing your tex) on flipping 180 to left.
Your download was actually 299 on my machine, but even that for a game jam is pretty hefty. I switched to Godot to do some jams, and even though I LOVE UE, Godot is growing on me, particularly for small projects and game jams. 3D is also very doable, which surprised me.
Anyway, nice job, project was fun.