I have created a new property set definition and added two manual property definitions and applied this to all objects.
Every object on the drawings has distinct values for these two properties. These property values show correctly on the Extended Data tab of the Properties palette.
I have published to DWFX with AEC property set data set to 'Include'. In the resulting DWFX in Autodesk Design Review I can select each object and see the standard properties but not my special property set data.