Well that's interesting.

I'm not sure what was going wrong before, but this time around I got exactly what you show above. I DO see a bump map, and I DO see a relection map. And I also now wsee a Specular to Roughness converter.  So the only thing that needs to be tweaked is that specular color.

The difference is, I shut Poser down in between, so there must have been something hanging around inside Poser that was causing GoPhysical to burp and not connect things right.

Here's the puzzle though. I show exactly what you show, but it renders fine on this end. No gray or black render.

I'm now officially at a loss. I can't reproduce the problem. I am totally stumped on this one, I'm sorry 8-(

I'm gonna pass my file over to Chuck (Nerd) since it's the same thing you have.