My character has 15 different materials assigned to different parts. In this exemple I assigned the new emissive material (through blueprints) to a bunch of them (ignore the boots, I didn’t assign to them in this exemple but they work too);
Now in the next image I have used the exact same set up and added the upper body material to also be set with the emissive material, and this happens:
If I try to set to only the upper body, it gets the same checkerboard material. Only 3 materials have this problem (the upper body material, the skin material and the inside of the mouth).