I'm running SW Professional 2015 SP3.0 with a toolbox library installed locally.  I checked to make sure the toolbox add-in is loaded and is set to generate new files instead of configurations when creating part sizes.

In an assembly when I right-click on a toolbox part and select "Edit toolbox component" and then use the Add button to add a part number and description to the list

-and click OK, the added part number and description won't be listed if I go back into "Edit toolbox component"

I'm trying to figure out why this is happening.

I looked into it a little further and discovered the following:
The updated description is added to the configuration properties of the toolbox part, but not the partnumber (which according to the help is supposed to appear as a user-defined part number in the configuration properties)

I read that using the Add part number tool in "Edit Toolbox Component" will update the toolbox database, but looking at the list of part sizes, I'm not seeing any evidence that my added sizes made it to the database.

Can anyone shed some light on what may be causing toolbox to not update or retain the sizes?  I've never had my head wrapped around all of the subtleties of toolbox, but until recently, I'd used this tool without any trouble..