Answer
To get the mass in a CATPart it’s important to put the material in the correct place in the document. The correct place to put the material is in the Part (and NOT in the PartBody). It’s important to follow this rule since the material in SmarTeam profile card will be taken from the part properties. If you put the material in the PartBody, SmarTeam will not show any material in the profile card.
In the link below you can find procedures step by step how to do it.