I have a key model that I made that I have imported into Poser, scaled to the size a key would be based on a typical Poser character as a reference.  When I render the scene the key is black and its shadow is a square.  If I scale the key up by around 30% the keys materials render correctly but the shadow remains a square.  When the keys is scaled up by about 50% the materials and shadow render correctly.  If I leave the key at its original small size where it renders black, but add another object to the scene that is larger, like a character, the key then renders correctly with materials and shadows.  I  have even tried adding a character to the scene and turning its visibility off to see if the key will render correctly at its proper scale but it still does not work.  I tried this out on two other computers with the same result so I'm guessing this is a Poser issue.  Is there some Poser render setting that I am missing that corrects this or is it a bug in Poser that I will just have to workaround.

This is a known bug, and you've parsed it out exactly. 
Very small props won't render on their own.   They'll show when another
larger prop is in the scene.  

If you want a picture of the key on its own, you could start with a
larger 'canvas' than you need, put a larger item off to the side, then crop.

ockham,

Thanks for the confirmation that this is a Poser issue.  Its a very peculiar bug.  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.

You might look at either using ray-traced shadows or  checking the shadow camera and zooming it in .

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.