Hi @docking9,
Thanks for providing the information we requested! You mentioned that enabling the LOD transition setting makes it somewhat go away. I wonder if it’s related to a known bug in the default tileset material, where the dithering effect causes weird visual artifacts.
Could you try the workaround I outlined in this other forum thread, here? If that solves your problem, great! If not, we’ll keep trying other solutions.
I also noticed that you’re using an older version of Cesium for Unreal. We always recommend updating to the latest version of the plugin 
If you’re worried about things breaking, you can make a copy of the project before changing the version.
Either way, let us know how that material fix goes and we can keep troubleshooting from there.