When I update a FBX link in 3ds Max that i exported from Revit I end up getting a bunch of MultiMat_XX layers. I've isolated a few of the MultiMats and they seem to only have one material applied to them. When I orginally linked the fbx file there wasn't a problem. All of the layers were named after the material associated with them. The multimats only appeared after a few updates of the link. Also when I linked the file I choose to seperate by Revit Material. Is there a way to make it so that we don't have the MultiMats? What is causing the MultiMat?
If this is the 2013 version then try linking directly to the .rvt file through manage links instead of using the fbx method
and select the view you want to work in.
If you are in 2012. then disregard above information.