Hi, thank you very much for sharing this workflow. And look really nice result.
However it's quite strange in the first case. It was material with colors only ? I'll try to reproduce.
they did have colors only, but they were emission shaders and weren't really mapped to the model like the ones I'm using now are.
They worked for blender, but not for anything else, basically. I had got into the habit of using them so I didn't need a light source in blender.
