The Courier is currently set up to be disabled based on an OnUpdate() event timer that checks every 10 seconds to see if the player is no longer in the same location he is. This can lead to the remote possibility of him appearing somewhere to make a delivery to the player but then never being disabled and returned to his regular cell again once the delivery is made. If this happens, the system deadlocks and will not allow him to make another delivery when called for, because the quest will already be running but will be unable to complete that delivery until the player finds him and talks to him in person to force the issue.
Rather than registering for a continuous OnUpdate() event, it would be more practical to have him register for a loss of LOS event after the deliveries are made. Using this method, once the player is no longer looking at him, the control quest will stop and return him to the holding area. This will entirely prevent the potential deadlock scenario.
Issue Data
Issue #32768: The Courier may not always be disabled when expected due to update event timing