I believe that you need the ACC mode to be able to turn the rails and the center magnet ON/OFF. Switch mode is only momentary. Program the SC-2 back to standard with 2 ACC and four switch ports, Use the ACC ON/OFF function to mimic holding a button and releasing when finished.
EDIT_ the SC-2 Manual shows the momentary terminal of the ACC port connected to the center magnet and operated with AUX1 - so, the activation rails for dumper car and such would need the ON/OFF terminal