Blue Iris

I just setup MQTT messaging from Blue Iris 5.3 and I am getting regular messages from BI with payload "stopped". I found this message on page 168 of the manual, but not what it means. What does this mean? BI is still running...so its not that the app has stopped.

My trigger ON messages are arriving at the MQTT broker, but the OFF messages are not. Each camera is set to "de-trigger" after 20 seconds, and I have an on-reset MQTT message setup.

Is this correct? Should de-triggering cause the off message to be sent?

Trigger Off payload works fine here. I've not seen "stopped" before. Must have a look.