Dave R,
Okay, I had to go to the Windows Apps to remove it.
Here's what I discovered.
I believe that any material in the model that I've previously exported using datasmith is renamed.
With the plugin disabled, the list of materials in the model still have all the numbered names (mat001, mat002, etc).
When I select any material in the Material Palette that isn't in the model (and hasn't been datasmith exported) it's original name remains in place.
When I select a material from the palette that IS in the model it has the matxxx naming.
I guess it's something datasmith has to do for import purposes.
theVonZipper