I had/have a problem that may be related in that, when I first got Poser 2014 I did a portrait render in Luxrender, via reality 3, using the Unimesh method the join at the neck is visable.  Going back to traditional skinning cleared the problem.   I have not used the combination since but I suspect from what is seen here is that it would be the same at all the joints.

 

 

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.