Glitchy flashing on every object

So, I’ve just recently started working on a new game, and everything was going fine. Today I fired up UE and all the objects in my game were all glitchy and flashing. It looks similar to when you have normals that are to closely overlapping. Also, it’s not just on the object I imported, but even on standard cube actors, with standard materials.

Here is a video with the glitch:

Hopefully someone could help me out with this. Thanks!