Big empty space for no reason

This happens every now and then after playing a fullscreen game. bspwm acts like there's a window there taking up space, but there is no window there. It doesn't have a title or anything. Restarting bspwm does not make it go away. I don't think it would matter, but the game that causes this is DUSKWORLD. It only happens sometimes, and goes away on restart. Anyone experiencing the same issue and know what the problem is? Or how to fix it? Thanks in advance