We've confirmed that all systems are back to normal with no customer impact as of 10/22, 06:40 UTC. Our logs show the incident started on 10/22, 06:00 UTC and that during the 40 minutes that it took to resolve the issue some customers experienced Alerting failure in East US region.
Root Cause: The failure was due to an issue in one of our dependent services.
Incident Timeline: 40 minutes - 10/22, 06:00 UTC through 10/22, 06:40 UTC
We understand that customers rely on Log Search Alerts as a critical service and apologize for any impact this incident caused.