Can you please tell us what version of Unreal Engine and Cesium for Unreal you’re using? The Cesium for Unreal version is found in the lower-right corner of the Cesium panel in the Editor.
Sure, UE 5.2.1 and Cesium for Unreal 2.11.0.
Ok, thanks. That means you’re crashing here:
I’m not sure why that might be, though. Are you certain that your custom material is valid at this point? It might help to give us some more details about it, such as how you’re creating and configuring it.