Alerts aren't being evaluated


I wrote a small application that generates ~50 panels and the output is the dashboard’s json.
I then create a new dashboard by importing that json.
Each panel in this dashboard has some alerts configured.
I set the evaluation interval to 4 hours and 12 hours later, all the ‘hearts’ icons are still white, indicating the alerts haven’t been evaluated yet.
So I changed on of the panel’s alert interval to 1 minute, and the alert was successfully evaluated soon after.

So what should I do now? Why does the alerts aren’t being evaluated? Does it has something to do with me creating the dashboard via json import?

Version 4.6.3