We've confirmed that all systems are back to normal with no customer impact as of 10/28, 18:30 PM UTC. Our logs show the incident started on 10/27, 09:31 AM UTC and that during the impact hours that it took to resolve the issue customers from multiple regions experienced Watchlist queries returning partial results, which may result in missed alerts.
Root Cause: A Code change in backend service caused the partial results and missed alerts when using Watchlist.
Incident Timeline: 10/27, 09:31 AM UTC through 10/28, 18:30 PM UTC
We understand that customers rely on Azure Log Analytics as a critical service and apologize for any impact this incident caused.