I have Arnold selected as my renderer. In the material manager, I select CREATE>ARNOLD>SURFACE>STANDARD SURFACE. The material window opens with all the settings, but the material icon in the manager comes up black. I can adjust the shader, rename it, drag it to an object, and it correctly covers that object in the IPR window. Yet, the material manager icon remains black. I suspect I have some setup parameter wrong. How can I fix this?