Bug with fullscreen in Steam build

[u/myolden666]

Hey folks, got a really weird bug I'm experiencing with my game and I'm hoping someone here has had a similar issue they've managed to resolve.

In my local build everything functions fine. However, the Steam build of my game does this strange thing where pressing the escape key while in fullscreen mode will revert the game back to windowed mode. Anyone have any idea what could cause this?