I have a very odd problem. My model looks perfectly fine with diffuse map on it and in Substance Painter too, but when I put my normal map on it it shows dark polys. The normals are in the right direction and I also tried to change the smoothing settings. But nothing worked. This never happened at my other models, only at the cars. (There are two more, where this issue is happening).
This dark patches also are shown in our own engine. I suspect there is something wrong with the tangent space, but I don't know much about this stuff. I tried to export it as FBX with Tangent Space checked on, but this doesn't helped either.
How you can see, the normal map is also fine. The place where the door sits is flat and shadeless blue.
Please can anybody help? This is very important for my work.