I keep having this issue with my viewport flickering, especially with objects in the scene. I have noticed this happens the most with FBX models using morph targets.
You can see in the video, but at certain camera angles and distances, the models flicker. I would normally work past this, but the movie render queue calculates all of this flickering into every frame, so it is just as bad if not worse when trying to render it out. However, when I select the skeletal mesh, it goes away.
I have updated my NVIDIA drivers to the latest. No fix. I have also tried turning on and off all lights, post process volume and other fx to see if there is a problem. The only time this problem seems to go away is when the Path Tracer is turned on.