I stumbled over a strange Error, never experienced it before:
I got a polygonal character, deformed by a lattice box, this box is skinned to a spine controlled by an IKSplineHandle.
When I now rotate the character (it's root joint/the controls, doesn't matter) 180 degrees, it's geometry turns/fades to black, same happens when I render the scene. I tried to assign several shaders, made a new scene and imported/referenced it, however, the problem stays.
If I just rotate the geometry itself the shaders behave normal...
If anyone ever had the same issues, I'd be glad to hear from it.
Update: If I turn on Display>Polygons>Tangents, I see that these rotate wildly...Although I know that's got to be the problem I'm still lost on a solution to this, everything deformed by the lattice shows this behaviour.:shrug:
Workaround: If you ever experience such, smooth your character/convert it to SubDs with history (Proxy Object). Worked fine for me since I'm rigging a lowRes-version of the character, but I'd still love to know why this occurs.