Could you please provide more information about the issue? For example, how are you trying to change the mesh’s color? If possible, could you also please provide some screenshots for reference?
If you happen to have something in the Texture ID field, try removing it and then changing the mesh’s color again. However, I’m not sure this is the problem you’re facing.
Without any visual provided examples of how the issue currently looks like, it’s hard to tell how to fix it.
If possible, I’d like the file with the provided mesh.
If not, then if DoubleSided is turned on, turn it off. If you see any changes like a color you’d wanted to provide, then the case might be with the mesh having faces on the inside. [decals, textures and etc. are affected to that]
Like provided under, try changing texture color id to zero and then remove it.
I am currently having a similar issue to OP and the solution provided doesn’t seem to work. I’m trying to change the color of the meshparts on an NPC, but the color won’t change despite the BrickColor being correct. There are no decals or other objects changing the color, DoubleSided is off, and the texture ID field is completely blank. Is there anything else I’m missing?
Remove object and see if there aren’t two by chance.
Unlike some situations, apparently meshes contain SpecialMesh or the different types that change color not based on BrickColor or either Color but by VertexColor or Vertex, not sure.
Add Body Colors to the Grouped object and check if it changes colors.
Does it affect the inside of the mesh?
Did you attempt to try removing the Pants and Shirt and see if the clothing does not affect it? Perhaps the pants are intentionally with the gray colors on them.