We've confirmed that all systems are back to normal with no customer impact as of 08/21, 03:35 UTC. Our logs show the incident started on 08/21, 03:00 UTC and that during the 35 minutes that it took to resolve the issue all the customers with workspaces in East US experienced data access issues in the portal.
Root Cause: The failure was due to an issue in one of our dependent platform services.
Incident Timeline: 35 minutes - 08/21, 03:00 UTC through 08/21, 03:35 UTC
We understand that customers rely on Azure Log Analytics as a critical service and apologize for any impact this incident caused.