A workflow such as a rule or monitor requires that its frequency be greater than zero.
The workflow indicated in the alert has been configured with a frequency of zero.
Review the alert details to identify the rule, monitor, or other workflow that generated the alert. Check the overrides for the workflow. If an override for frequency is configured as zero or the default configuration is set to zero, modify the the value to be greater than zero. For instructions on setting overrides, see How to use the Monitor Overrides (http://go.microsoft.com/fwlink/?LinkID=117777).