How to Trouble Shoot the Alerts frequency

Having trouble understanding the frequency of Alerts.

In the below image as you can see the Alert did not trigger in 2 instances.

Alert parameters
Evaluate Every - 10 seconds
Is Above - 50

The first green peak could be missed depending on the time range and reducer in your alert query condition.

The second red arrow is pointing to a peak, but the alert is already in alerting state at that point and soon after goes back to green.