[SOLVED] Please help: Xbox One Controller is connected to the PC but doesn't work in the game itself

[Thinking of ♥♥♥♥♥]

EDIT [SOLVED]: I figured it out. Apparently you just have to enable big picture mode (top right-hand corner of the Steam interface to activate) and it works for me. I'll just leave this here in case other people are having similar issues.

Like the title says, I'm trying to play UNIST with a controller, and while it appears in my PC's devices menus as being connected, it just doesn't work in the game itself. I have no idea why that is. Does anyone have any similar experience and can offer a fix?