In Maya any duplicated a mia_material, mia_material_x or mia_material_x_passes, do not display the textures in the hardware display properly. You end up with a bunch of black objects.
You can run this script to fix the problem.
Download the script and copy the mel file in any script folder, call the command fixMiaHardwareShading() in the script editor to execute the script.
Enjoy textures in your 3d view once more!