Thanks for bringing this issue to light keppel.

Quote - Playing around with the limits of the bug I found that I could add a one sided square from the Poser primitives props folder and scale it down to 0% so that it is invisible but for some reason because of its presence in the scene it enables the proper rendering of my key prop.  Strange indeed.

I wonder if the square needs to be in camera's field of view, or if it will still work if it is behind the camera.