I would do the usual things:
- Verify that the Notification object is created from apply rules.
- The config validation will log warnings for non-matching apply rules.
icinga2 object list --type Notification --name ...
- Verify that the default state and types filters match
- Verify that the User object doesn’t filter away the notification event
- Enable the debug log and trace the notification being triggered up until the script is fired, check whether specific conditions hinder that.
More on that in the troubleshooting docs.
Cheers,
Michael