I have never had the problem where I have lost half of a particular peice of clothing but I have had times when pokethrough has appeared in a render that was not there in the preview.   It seems more common with some items of clothing but I have not been able to pin it down. What I have noticed is that, on occasions, the slightest change in the scene and the pokethrough disappears.  Moving the camera a fraction or even changing the camera but with the same point of view can rectify the problem.  

Interestingly I seem to get it less with the latest release of Poser and as, up until recently, I had never used anything but Firefly I did not know that it was Firefly specific.    Now I am playing with Luxrender I will have to try and find one of my scenes that dispayed it and try again.

As to what causes it I do not have a clue unfortunatley.

 

 

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.