I went and saved the Materails as suggested- under the depreciated segment (which I forgot about, thank you) of the menu.  The DSA file was made, along with a PNG file...that saved oddly.  Armor Base.dsa   and Armor Base.dsa.png

I noticed the .duf files had the same issue with the .png- the png saved Armor Base.duf.png

I went back and removed the extra extension- be it .duf or .dsa - to have them saved as .png.

I then went into the mt6 file, changed it to a pz2 and inside the editor switched out the MTL section of the data with figure.

That. in DS3, had all of the files show in the menu, but only half uploaded onto M4.

What frustrates me is that I've saved character files many times before, for paid commission work, and never had this issue.  That was in DS 3 Advanced, though.  

I'm more than a little irked that everything's changed, and it just simply cannot be spelled out in one place how to actually save a character file from start to finish- I've tried going through the "documentation" offered for Studio 4.6, but that's a joke since more than half of it is either in "Draft" or not started.

I hate to say it, but I may end up saying to heck with it and leaving it for DS 4.6 and Poser Pro, even if that means having to leave so many other people out of the loop if I can't figure this out.

All I wanna do is save my character's skin textures/settings in DS3 Advanced!  Seriously.  Urg.