Seems to be an issue with laptop GPUs switching between intel and NVidia. They won’t fix it according to this issue: UE-20675
Similar question:
EDIT:
I fixed the glitches for myself by forcing “Integrated Graphics” on the editor in my NVIDIA Control Panel.
Executable path: “C:\Program Files\Epic Games\UE_4.18\Engine\Binaries\Win64\UE4Editor.exe”
It works for now, but might give performance issues while testing in editor. I haven’t stress-tested yet.