Notification not working

Like other recent posts, recently, my notification emails suddenly started failing on a regular basis. The failures began on 15-Aug, with the last successful email being sent on 12-Aug. Before this date, emails sent successfully.

Troubleshooting following this guide:

1. Check the notification log: Notifications are being scheduled and are appearing correctly in the notification log, however all notifications have a status of “Error: The notification was set as “Scheduled” but the cron task is not found (asynchronous)”
2. Check the Async option: I previously enabled the Async option, but notifications are failing even with async enabled (according to the notification log)
3. Set up a cron job: I previously set up a cron job on my server, and other scheduled tasks (such as publishing posts) are working appropriately. However, notifications are failing (as verified by the notification log).

I’ve also attempted to reschedule notifications, but so far those are failing as well.