I get this weird error with my normal map plugged in, but not without it being plugged in.
It seems to restrict lighting from one direction, making it shadows or something.
without it plugged in:
Here is my material normal map setup:
Is your normal map texture set to normal map for compression, and have you tried flipping the y channel? when you set it to normal map compression it will uncheck the rgb box.
it seems to work now. apparently if you have a non normal map set as default normal map in a parameter in an instanced material it will bug out