Anomaly alert stuck in Monitoring

Hello, I'm working on an anomaly alert and I'm just trying to understand it.

I've created a Timer Thing with a number property called "value" and I've set an anomaly alert on this property.

This property changes due a subscription whose code is quite simple:

me.value += Math.random() * 3 - 1.5;

So I've got my value changing every second.

My anomaly alert status went from Initializing, to Calibrating and then to Monitoring.

It is stuck now.

I don't get how does it switches from Monitoring to Training.

Thanks