I have a rendering that i need to get to marketing and i'm beside myself. The assembly i am trying to render has weldments, parts, routing pipes etc. When i select render preview, i get an empty screen. no geometry, only background. if i change the environment the preview updates. if i open other parts or sub assemblies they render just fine. Only 2 sub assemblies will not work. the top level, and the routed pipe by itself. thoughts?? thanks so much in advance!