Hey,
Today I wanted to set up Cesium in my new UE Project. I am using UE 5.1.1 and the Cesium Plugin 5.1.0. When I add the Cesium SunSky my Level stays black. When Adding basic Cesium World Terrain + Bing Maps Aerial imagery The Sky turns light-blue and noisy and I can only see the outline of mountains. I tried using other tile sets but everything just shows up black. I tried using basic UE Lighting but still nothing is visible. I also tried restarting the Project but since then everything just remains black.
I have used Cesium just a couple weeks ago without any problems. So I’m not sure what’s wrong. This seems to have happened after updating the Plugin. Any Idea what this is?
I’m not quite sure what to make of those issues. First thing to try: install a fresh copy of the Cesium for Unreal Samples project and see if that works.
I realized it was because of my Sublevel settings. 
Sorry and Thank You~