look through the different visualisation buffers to determine what channel causes this. could be base color, could be reflection or sth like SSS or specular, emissive, ect.
how does it react to light? is it self illuminating or is it absorbing light too much?
it is probably an issue with the master material that might not be fit for nanite for some reason. so try throwing on different materials, first different instances of the same master mat, then try other materials based on different master materials.
maybe some kind of dead connection in the master. an outdated material from 4.x or sth?
Generally:
turn off / switch out stuff till it works, then determine the difference