If you have a multi-display setup and are suddenly experiencing issues with games, it's probably because Microsoft messed up.
As part of this month's Patch Tuesday cycle, Microsoft installed cumulative update KB3213986 on your Windows 10 system. While this update fixes a wide variety of issues, it also contains some bugs that introduce new problems.
In the release notes, Microsoft explains users may experience delayed or clipped screens while running 3D rendering apps like games on systems with more than one display. As a workaround, Microsoft proposes running the game with just one monitor connected, or to run it in windowed mode.
Presumably, Microsoft is working on a fix but it's unknown when this issue will be resolved.