I will watch this thread with interest as it has happened to me in the past.  Mine were not mulitiple scenes just one V4WM.  I could use the figure in Reality a few times then parts of the body would go back to glossy and some on the image maps would change to greyscale from colour.  Never happened on a regualr enough basis for me to duplicate at will and, as I only had one figure it was not a major problem for me to correct.  Strangely I cannot remeber other parts of the scene changing, just the figure.

 

 

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.