I have a tree with 3 material ID's in my trunk and branches, and 3 ID's in my instanced leave objects.
I've made a multi material with 6 materials. When I press update in the MultiMaterial rollout of the instance geom for the leaves, it will reset the first 3 materials. ID 1 is turned in a Standard material, while it was a vraymtl, and ID 2 and 3 are resetted into standard materials with no bitmaps etc.
So every time I hit update I need to populate my multi/sub mat again...
I think this is a bug?