Open that model and check the properties. Make sure weight property is set to part property and not parent part.
This is you may see
This is how you need to set it. Uncheck "Copy custom properties" in the save bodies property manager.
Ans then set the weight in the saved body properties to mass
Also check these posts
For older versions
This is the perfect response! Thanks a ton. I went back and tried this on a new model and the properties are no longer linked to the parent.. perfect..
One caveat seems to be that I cant get my existing part files to update.. I went to the model in my screenshots, updated the save bodies feature and removed the "copy custom properties" check, per your guidance. The command completed and i saw an "updating" popup. However, the saved body part weight property did not become de-linked from the parent part.
For good measure i made a backup, then removed the saved body part files, and the save bodies feature from the parent, then recreated everything again using a new save bodies feature. This worked, but deleting the part files, and the save bodies feature and starting over isn't practical because the first set of saved body part files had additional features that weren't in the original parent model.. I'd have to manually re-edit each saved body part again. *shrug*
Can I manually de-link the saved body properties from the parent? If i cant get these particular part files to de-link from the parent, it wont ruin my life. The next project I'll have the custom properties settings correct and this wont be an issue to the very helpful reply.. Thanks!