If you’re creating a Tileset manually, you also need to add a Raster Overlay Component in order to get textures. Asset ID 1 (Cesium World Terrain) is geometry only, and then you can drape a number of raster overlays on it, such as Bing Map Aerial imagery, etc. The easiest thing by far is to use the Cesium Quick Add panel after signing in to Cesium ion:
I’ve occassionally seen that LogUnrealMath error and I’m not certain what causes it, but it usually doesn’t cause any actual rendering problems.
The latest Cesium for Unreal release also shipped to using Material Layers by default, so if you’re using a custom material with your Tileset that could cause some problems. We’ve aimed for backward compatibility, but it’s possible we haven’t achieved it perfectly.
But if the unmodified Cesium for Unreal Samples project is missing textures, that’s strange. I just checked and the latest Cesium for Unreal Samples project on the Marketplace contains valid Cesium ion keys and appears to be working well. The first thing to check is that you’re definitely using the latest Cesium for Unreal Samples project from the Marketplace. If that still doesn’t help, please share more details about which Level(s) aren’t working as well as some screenshots of what you’re seeing.