I have another one, if I make a SubD then it shades it ok, until I rotate the view, then the SubD becomes wireframe, until I click on the object or do something else. If I extract the rendermesh then that shows fine, but there are some edge errors, I have a naked edge color, and it shows both naked and joined edges at the same time.
Here are the different states:
Original mesh, SubD, Extracted Render mesh, exploded rendermesh:
And same view if I do a small manipulation:
Also note that the SubD "edge curves" are thinner than the rest, I don't consider it a bug, I actually like it, maybe the meshes could benefit from that feature too. Unless it is something that slows the display down of course!