Looking through past posts I see this problem has been addressed often. I have tried many of the offered solutions unsuccessfully. I have a hi poly sculpt that I have normal mapped to a lower poly object. I would like to see the effect of that normal map while painting in a diffuse color slot in texture paint mode. The map looks fine while in the render viewport setting but does not show up in any other viewport setting. Painting while in a render viewport is too slow and not a viable option. To check my basic settings I made a simple scene with a plane object normal mapped with a sculpt and was able to see the mapped result fine in texture paint solid or texture viewport. So it seems the process does work but I cannot get it to work on this particular file. Is there a poly count limitation at work here or am I totally missing something obvious? Please see attached images demonstrating this issue.