We've confirmed that all systems are back to normal with no customer impact as of 2018-08-10 00:56 UTC. Our logs show the incident started on 2018-08-09 19:16 UTC and that during the impacted time range 121 Azure Audit Logs customers comprising 112 subscriptions in South-East Australia and 130 Azure Audit Logs customers comprising 428 subscriptions in West Central regions experienced a loss of all logs of data type "AUDIT_LOG_REST_API".
Root Cause: The failure was due to a code regression in a service module that has been reverted
SEAU Incident Timeline: 3 Hours & 36 minutes - 2018-08-09 22:20 UTC through 2018-08-10 00:56 UTC
WCUS Incident Timeline: 5 Hours & 8 minutes - 2018-08-09 19:16 UTC through 2018-08-10 00:24 UTC
We understand that customers rely on Azure Log Analytics as a critical service and apologize for any impact this incident caused.