Operating system: OSX 10.14.2
Blender 2.80. 2019-02-08
Short description of error
When texture painting the bump map (in Cycles or Eevee) in the 3d view port when material view is selected, you are only able to see the bump map. You should be able to paint on it while seeing the full material (the Difuse map with the bump map effects). Very difficult to add or remove height if you are unable to see the diffuse map on the material. When you switch from texture paint to object mode, it shows correctly, but when you switch back to texture paint, you can only see either the bump texture (as a flat texture) or the base color map, but you do not see the effects of the material with the bump.
Exact steps for others to reproduce the error
Create a plane. Add a material to the plain. Go into texture paint. Add a texture slot as a base color. Then add another texture slot as a bump map. In the 3d viewport, you can only see one texture or the other, and you do not see the effects of the bump. Switch that view to object mode and it shows fine.