I have had a problem with the render where it has finished but a large amount of the lower part of the render is grey.  This normally happens when it is a large render and you need to scroll up or across render to see the full scene.  Strangly, often when I try to scroll the whole render appears so, in my case it could be a display issue.  Only noticed it with PP2014 though, not PP2012.

 

 

I use Poser 13 on Windows 11 - For Scene set up I use a Geekcom A5 -  Ryzen 9 5900HX, with 64 gig ram and 3 TB  storage, mini PC with final rendering done on normal sized desktop using an AMD Ryzen Threadipper 1950X CPU, Corsair Hydro H100i CPU cooler, 3XS EVGA GTX 1080i SC with 11g Ram, 4 X 16gig Corsair DDR4 Ram and a Corsair RM 100 PSU .   The desktop is in a remote location with rendering done via Queue Manager which gives me a clearer desktop and quieter computer room.