A user can enable failure notifications for automations in their profile settings. Reference: Notifications
However, despite the automation failing several times, only the original notification of the first failure is delivered.
Resolution
This is as designed.
Since automations can be run every 30 seconds, we want to avoid spamming the user with notifications. We therefore have a 6-hour window after a failure during which the user will not receive another alert.
Another can be sent after six hours.
Qlik plans to reduce the window from 6 hours to 1 hour. No estimated time for this change is known yet.