Help - scheduled event not working in UI7

Hi - I have setup a scene to do a scheduled trigger to ensure my front door is always locked in UI7. The trigger is Every 20 minutes to lock the front door. The event triggers the first time time but now it shows up in the scene having the same Next Run date and time as the Last Run? It doesn’t advance 20 minutes and doesn’t try to lock the door? Is it because the lock is already locked? Is there a better way to do what I am trying to do.

Thanks in advance