Notifications to issue owner when the planned completion date changes

Is there a way for the issue owner to get notified when the person assigned to do the work changes the planned completion date/time? We see the option for the assignee to get notified when the date changes on an issue they are assigned to but not the reverse. We thought the owner would get all of the notifications but we tested it and they are not. We also made sure all notifications were turned on to instant.

We are basically trying to find a way for the owner to get notified if the due date/time isn't going to be met. We had tried a custom field but we couldn't set a notification from it. The best we got was to set it to display as a system update. But the Owners specifically want to get notifications and we are struggling to fins a successful approach.

Any ideas?