Assigning material to inserted part...?

I often work with multi-body parts where I assign different materials to individual bodies (by right-clicking on one or more bodies in the feature manager). But if a part is inserted, any original material is deleted (why?) and the option to apply a material by right-clicking is missing (there is no Material tab in the menu). Can anyone explain if this is a feature or a bug?

SolidworksParts And Features