Today I started seeing the following error in the console for my hosted feature layer in the scene viewer (as well as JSAPI 4.0 apps running locally):
"Image from origin 'http://static.arcgis.com' has been blocked from loading by Cross-Origin Resource Sharing policy: No 'Access-Control-Allow-Origin' header is present on the requested resource. Origin 'http://tomwayson.maps.arcgis.com' is therefore not allowed access."
I suspect that is also the cause of another GraphicsLayerView3D error I see in the console:
"GraphicsLayerView3D.js:18 Uncaught TypeError: Cannot read property 'equals' of null"
I was able to view this same layer in this same web scene just yesterday.