Updates Green Fix
When the model is referenced-in to the rig file, any model changes are automatically updated in the rig:
When the model is referenced-in to the rig file, any model changes are automatically updated in the rig: However, it is possible for shader-issues to occur “Green” shader issue:

This usually occurs with objects that have “per-face-shader-assignments”. When deformers are applied to objects in Maya, the objects are duplicated, and so the information about material assignment is also duplicated: However, if the information about material assignment on the original is changed (This can happen as part of model-changes) Then the rigged model might not be able to determine how to update the materials. This function will attempt to find such issues,and automatically update the assignments.