As a designer, I have made a hud to apply all PBR or BP parameters on faces of some items with one hud and one click only, and that includes 10 K textures and 2.5 K materials.
In PBR, some faces of my Mesh items can't be set with a material, they "stay" in BP.
Issue is reproductible on about 10% of faces on about 5% or Mesh items.
Have you heard about that ?
Is it planned to be fixed ?
I can show you inworld if you need more info and/or some Mesh items to see what happens.
I use Firestorm.
I have the same issue with all versions of Firestorm for about one year.
Yours,
ophelatex.demonia
designer and manager of DomiNation & Lilith shop (https://marketplace.secondlife.com/stores/230382)