Same issue here.
I think it's model complexity. I have other layers that render out to hidden line fine in my view ports. The layer that doesn't render to hidden line, and stays at wireframe without any prompt explaining the error is a complicated 3D model partially imported from a Rhino file.
Like I said, other layers render to wireframe fine. Also when I'm editing in the complicated design layer and try to view as hidden line it throws up an error stating that it's out of memory. (Good thing I have 16 gigs!)