I am also having issues with the Tax Parcel Viewer application and using a parcel layer with a joined attribute table and fully qualified field names.
Using Firefox & Firebug, I can see that the data is being returned correctly from the query, but all that shows up in the search panel is "parcel not found at specified location" if I click on a parcel, firebug shows the correct data returned, but no parcel selection or info window, just a popup that says "parcel not found at specified location"
We will be migrating to the local government data model in a few months, but I need to find a workable solution now.
Anyone?