Turn off Triple Buffering.
Spent Days trying to figure this out and now I'm getting a clean 60 - 96 fps on my 1080ti's (x2) I prefer msaax2. taa fxaa all off. Everything else high or Ultra. No flickering lights and background. I do have the Profile fix done in Nvidia Inspector, but that wasn't stopping the flickering, but just reducing the frequency of occurrence. Vsync On