Azure Endpoint monitoring not working

I have a Web Api that exposes a ping method to call. I have set up endpoint monitoring to hit that method of the api.

I have also created a new rule on the uptime metric available for the configured end point.

The rule is set to trigger if uptime is less than 100%. Currently the end point is returning 401 response, still the alert is not getting triggered. I'm also not getting any emails around it.

I checked that the rule is enabled.

Could someone please suggest, what might be going wrong.

MS