Solidworks RealView in Assy Mode

[claymation]

I have 3 parts in an assy that were assigned specific materials in part mode. When I edit the complete assy and say... extrude cut into the 3 parts, I lose my realview.

I can edit an individual part and realview ok... just seems to disappear when I edit the entire assy.

Am I making any sense???

cg