Final Update: Saturday, 15 February 2020 01:53 UTC
We've confirmed that all systems are back to normal with no customer impact as of 02/15, 01:00 UTC. Our logs show the incident started on 02/14, 23:30 UTC and that during the 90 minutes that it took to resolve the issue some Azure customers experienced latency in Activity Log Alerts.
Root Cause: The root cause has been isolated to a backup in a storage queue which caused alert latency.
Incident Timeline: 1 Hours & 30 minutes - 02/14, 23:30 UTC through 02/15, 01:00 UTC
We understand that customers rely on Activity Log Alerts as a critical service and apologize for any impact this incident caused.