When creating a design for something like a plastic part with insert molded components, I have in the past used a structure like the one shown here, where the 3Dshape for the plastic part lives in a physical product and it includes parts within it.

The issue I am having, is that I am now unable to calculate the mass in BI essentials of the 3DShape for the plastic part.

How do I make the mass on 3D shape calculate appropriately?