You may need to assign the geometry to to the material! With the console selected, go to edit mode, select everything with A on the keyboard, then under the materials properties tab, click Assign on the required material!
Harris know this lesson very well. You have to apply the material to their respective motherly faces. It went something like that. Ok you caught me, I don't remember it very well, I say a lot of things, I can't remember them all. One day with Neuralink implanted we will though, but count me out, I'll go old school brain always.
https://cgcookie.com/community/18646-troubles-with-painting-across-certain-islands-in-3d-viewport
It's a long thread, but I sure learnt my lesson!
