*Solved* Unable to apply material to specific part

Axemeister

Hi there. I'm having an issue in 3.02 where I cannot apply my material but only onto certain meshes, as shown in the picture below on the two bolts on the front panels. All of them are duplicates of the same mesh and the others seem to be working fine.

 I've tried reimporting, merging/seperating all the meshes applying new maya materials etc but nothing seems to be working. 

I'd really appreciate any help with this!