While you were replying, I adjusted the recordset to include a GET[ID]. This allowed the radio button to return the correct value, so I deleted the original post, thinking I had found a solution.
However, I now only get the one unchecked value.
Added a new Repeat Selection and included your 'checked' code, but nothing changed.
Also added a new Multiple Update server behavior, similar to the checkboxes; same result.
Checked the wizard and found had I selected the wrong repeat field. When I change the repeat field, the wizard won't accept it (the top entry from the list always reappears). Tried multiple times; restarted DW; still same result.