Unable to assign materials, maybe a material property setting issue I'm unable to assign/view a new material(in this case it is "Leather_dark_brown") to an object. I think it has something to do with my material property setting, since it has no problem assigning other materials.
Cycles materials will display as a solid colour in the viewport, unless the viewport shading is set to material or rendered.

The material settings include the viewport colour to use for the material.