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Detection Model Management Exceptions endpointIp Field supports IP Address Range Values (ex. 10.205.100.0/24)

If the Workbench Alerts persists, navigate to the Workbench Alert and click "View Event"
This will show the Observed Attack Techniques App Event which triggered the Workbench Alert.

From Observed Attack Techniques App, ensure that the endpointIp value falls within the defined IP Address Range of the Detection Model Management Exception Values.