I'm having trouble getting my texture paint to show up in render/material preview I have this nice grainy white texture I've been using, and I want to draw some rust on it using texture paint. But the rust only shows up in solid mode view, and disappears when I switch to material preview or render view. Any clue on how to solve this issue? 

Here's a video of the issue: https://youtu.be/6w2wEEKd0CU

Thanks!
At the material preview the things get really brighter and the colors that you used are shades of white. I think your problem is because of this.