Form notifications not sent after field value changes when post edited in back end

Symptoms

Form notifications can be set to be sent when a custom field value changes (and matches some target value).

The notification should be sent whether the post is edited with a front-end form or in the back end, but in work in Forms 2.6.10 to fix various notification issues, this was handled incorrectly, and the notification is not sent after back-end updates.

Workaround

Fixed, but please be aware of https://toolset.com/errata/notifications-when-custom-field-value-changes-not-sent-if-updated-programmatically/