Nintex O365 Workflow failure should monitor 'Terminated' workflows and send out alert when it happens. We have a few incidents caused by terminated workflows but we weren't aware of.
This feature has since been added:
With this release we have introduced Workflow failure notifications:
- Introducing the ability to receive email notifications when a production workflow fails. Workflows can be configured to send notifications to the last user who published the workflow and/or the Workflow owner. These new options are available in the workflow publish dialog box, and at least one option must be selected before the workflow is published for the notification to be sent.