When comparing the results of the "Advanced Weight" calculation in NX11 and the "Mass Properties" calculation in NX2015 for the same data, the results of the "Warnings Generated by the Mass Property Calculation" change.
In NX11 "Warnings Generated by the Mass Property Calculation" gives more details on the components which are not loaded and why those were not considered for this calculation.
Whereas the same is not available in NX2015.
Solution
The current behavior is as designed. Unlike the legacy behavior, the closed part can be calculated in the mass management, which is an improvement compared to the old weight management behavior. Since the closed part is also calculated as other regular components, there is no need to have the warning for it.
Notes