Normal Map Not Applying at Runtime in Material Layer Blend

Hi Cesium Team,
I’m encountering an issue while applying Material Layer Blend at runtime for cesium texture mapping. The diffuse textures apply correctly, but the normal maps don’t seem to take effect during runtime. However, if I manually open the material instance in the editor (double-click), the normal maps then appear correctly without changing anything. Could this be a bug or am I missing something required to trigger the normal map application at runtime?