I spent the last 5 hours trying to remedy this problem or find a work around, I can't find anything online that will help me, I keep getting single faces that have incorrect UV information/Borken UVs (but only a few faces, not the entire mesh)
Here's the Mesh in Marmoset:
The bottom is directly from Blender, the top is what I export too Zbrush then Export out of Zbrush.
Shot from Zbrush, completely fresh UV, imported from Blender.
When I import the model as a fresh subtool the UVs are fine, but when I import over the existing mesh or try to copy-paste the UVs they return to this state.
I sculpt in Zbrush then export the lowest sub division out to Blender to unwrap, Then I import the Unwrapped mesh into Zbrush onto the existing Subtool. The mesh now has the new UVs but for some reason, even If my settings specify that the vert order does not change, 1-3 faces have the wrong UV rotation, It's killing me.
I've even exported the mesh from Zbrush, completely re done the UVs so the mesh should be completely fresh and identical again, but it STILL ends up like this.