We've confirmed that all systems are back to normal with no customer impact as of 12/18, 03:30 UTC. Our logs show the incident started on 12/17, 17:00 UTC and that during the 10 hours and 30 minutes that it took to resolve the issue 0.128% of customers experienced data latency for new custom logs.
Root Cause: The failure was due to a config issue in one of the dependent service.
Incident Timeline: 10 Hours & 30 minutes - 12/17, 17:00 UTC through 12/18, 03:30 UTC
We understand that customers rely on Azure Log Analytics as a critical service and apologize for any impact this incident caused.
Update: Tuesday, 18 December 2018 03:05 UTC
We continue to investigate issues within Log Analytics. Root cause is not fully understood at this time. Some WEU customers continue to experience data latency issues for new custom logs. We are working to establish the start time for the issue, initial findings indicate that the problem began at 12/17 ~17:00 UTC. We currently have no estimate for resolution.