We've confirmed that all systems are back to normal with no customer impact as of 04/20,15:00 UTC. Our logs show the incident started on 04/20,13:21 UTC and that during the 1 hour and 39 minutes that it took to resolve the issue some customers using Azure Log Analytics in East US Region may experience data access, data gaps, data latency and missed or delayed alerts.
Root Cause: The failure was due to a regression in one of the backend services.
Incident Timeline: 1 Hour & 39 minutes - 04/20,13:21 UTC through 04/20,15:00 UTC
We understand that customers rely on Azure Log Analytics as a critical service and apologize for any impact this incident caused.