Update: Friday, 23 August 2015 00:37 UTC
Root cause has been isolated to an issue which was impacting a subset of customers. To address this issue we have applied mitigation steps and working toward deploying a hotfix soon.
Next Update: Before 07:00 UTC
Sincerely,
VS Online Service Delivery Team
Initial Update: Thursday, 22 August 2015 23:17 UTC
We are actively investigating issues with Visual Studio Online in US region. Some customers may notice identity filter validation exceptions. Our DevOps are reviewing telemetry and actively working to fix this issue.
We are working to resolve this issue and apologize for any inconvenience.
Sincerely,
VS Online Service Delivery Team