I then reopen and Edit the ticket, clear 2 of the 3 check boxes and Update request. This works correctly, as the corresponding tasks are removed when I go to the Tasks tab.
However, if I Edit and clear all 3 fields and click Update request, SDP behaves as if I had all 3 check boxes set,
and shows all 3 tasks on the Tasks tab. No API calls or Rules are being used to create the request.