Here's the workaround. Add your fabric to the map; it's symbolized automatically. Add Data and browse to your fabric, go into the fabric, and add the ParcelFabric_Parcels feature class. Now open the symbology for your fabric layer that you need to modify. Choose import and then select your stand alone Parcels feature class. click apply and ok. Now, go back into the same fabric layer and you should see the Categories option return. Granted you have to set it all up manually now, but at least you can change symbols/add values.