It sounds like the 50018 was not set up correctly and you were using it as an On/Off switch rather than setting the correct option for solenoid motors which would explain why the motors were buzzing all the time.
Since we moved, we no longer have the layout that used Digikeijs. ?I do not remember setting CV47. ?We used the Digikeijs app to set up the switch decoders.
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At this time, we are just trying to decide what DCC system to use to run our new layout.