Customers transitioning from NX11 to NX1953, if they have not Saved their assemblies with Saved Mass Data, the Mass Status column will always have "unreliable" when Opened in the current versions of NX.
So are the options to Save all the parts or manually Update the Mass Properties?
Solution
In NX11 when saving Mass Data, the reference set used for calculating the mass data matters. Loading the parts into NX 1926 or NX1953, the NX function will check if the reference set used in NX11 is the same as reference set defined in the customer default to determine if the parts mass status are OK or not. You need to check what reference set that was used for mass calculating in NX11. (Gateway --> Materials/Mass --> Miscellaneous --> Mass Properties Reference Set Precedence)
In general, it's recommended that loading the NX11 parts into NX1953 for the first time is to recalculate the mass data by clicking on the "Update Mass Properties" button in NX1953. This will help to get a complete set of mass data which can support the display in the Mass Panel. (see the documentation "Generate initial mass properties for an assembly" noted below).
Notes
NX Analysis --> Advanced Mass Properties --> Generate initial mass properties for an assembly.
https://docs.sw.siemens.com/en-US/doc/209349590/PL20231101866122454.nx_analysis/xid1749004
Notes