Broadcast R20. Create a new scene, add a sphere. Apply the built-in Ceramic node material. Switch to ProRender, then render. End up with just some tiny amount of gray pixels. Then, add a plane and apply the ceramic material to it and re-render. It’s now acting like a light source (see attached sphere_plane.jpg which contains the two renders).
Most of the other built-in node materials all work as expected (e.g. Gold, Car Paint).