Materials after Subtraction not ready for exporting.

[Kalabedo]

I tested useGroups, to get different matrials before exporting my mesh. In three renderer everything looks right but after exporting the whole mesh has the color of the Subtraction. I checked it in Blender and it has two materials but they are simply on top of each other. Here you can see how it looks in Blender:

I read that your library is built around three-bvh-csg and there is an option to consolidate groups. Could this be the problem, that the materials are merged somehow?