When I first started using Verge3D one of the most aggravating things I encountered was the assign materials puzzle. Assigning materials to other objects just seemed to mysteriously work for some materials and wouldn't work for others until I learned this little secret.
If you find you have a materials that stops working in Verge3D or doesnt return after you have assigned it a different material, this tutorial will help you solve the problem.
This tutorial is specific to Verge3d and was done using Blender but the same principals can be used in MAYA and Max.