Whenever a backup operation is completed, it updates the status of backup in History log file and Alert table of the DB. If the backup alerts are not configured in the Alerts pane, the backup statuses will not get populated in the Alerts pane, even though they are recorded in the Alerts table in the DB.

The alerts “No backups in 7 days”, “No backups in 14 days” and “No backups in 28 days” are triggered based on the last backups populated in the alerts pane.

If the Admin has not configured “A backup job has completed with errors”, “A backup job has completed with warnings” and “A backup job has completed” as shown in the following screen shots, the alerts are not populated in the Alerts pane.

Hence it is showing that there were no backups for 7/14/28 days.