Due to the way the door contacts work on a monitored maglock, there is a tick box called "Leave door relay open during all 'door open time'" that should be ticked to avoid relay flutter.
From the controller screen.
Go to Reader > Miscellaneous Badge format
At the Miscellaneous Badge format screen find:
Leave door relay open during all 'door open time'
Put a tick into the tickbox >Save & Close.