Mouse will not move crosshair if moving up or to the left slowly.

[spinehaus]

I was having FPS issues, so I switched from fullscreen to borderless window. This fixed the low FPS, but now if I move my mouse up or to the left below a certain speed it will not register the input.
Moving it quickly works fine, and looking down or to the right is unaffected. My mouse isn't broken and it will move normally in the menus.