Can't get event to start with event.start

What am I doing wrong when I try to explicitly start a normal Event with this script call:

event.start

Here, event is a Game_Event which is set to trigger on Event Touch.  My script is running a patrol, and the event (guard) has detected the player and is trying to run into him.  But, even though the guard is pushing against the player, and I clearly see the start call executing, nothing happens.

Now, in my patrol logic, I control the event's location by using the event's move_toward_character method.
  
The event itself has 2 calls, and triggers on Self-Switch D being set to ON.  I've verified Self Switch D is on.  The 2 calls are:

Battle Processing: Guard

Erase Event

My script sets Self Switch D when the guard detects the player.  The patrol logic then speeds up the guard dramatically and runs him into the player.

What am I missing to get the event to execute?

I've split this question out into its own thread, as your problem sounds pretty specific and we'll probably need some screenshots and a bit of Q&A in order to solve, and I just didn't want to clog up the pinned topic too much.

I don't really understand if your problem is that you have ONE event that's trying to set its own self switch and then make that page start by a script call, or if you have TWO events and you've got one of them trying to make the other start.

Can you show screenshots of the event you're trying to start, as well as the event that has the script call to start it (if it's actually two events)?  Include the WHOLE event window - tabs, conditions, sprites, and all.  If there are multiple pages, show each page.