Using Rhino for Mac, with an dxf 2007 imported from autocad. One closed curve will not planarsrf. It looks as if it is stuck in wire image, (when all other layers render, shadow, etc), and it does not act as surface when using the drape command.
I have exploded and rejoined, re-imported from cad. All the other line work is exactly the same, and renders properly. I’ve tried selbadobjects and there are none. I’ve tried analyzing, etc.
Any advice is greatly appreciated.