It has been determined that this issue was caused by Microsoft ID TM186856Title: Can't view documents, create teams, or view organizational charts
According to Microsoft this issue occurred:
Start time: 2019-07-30 22:15 (UTC)
End time: 2019-07-30 23:30 (UTC)
An excerpt from Microsoft’s Incident covers how the issue affected the Teams CVI Service:
Final status: Our monitoring system alerted us to an issue in which an Application Programming Interface (API) was intermittently dropping connection requests, resulting in impact to multiple scenarios in Microsoft Teams. We've determined that a recent change to Microsoft Teams had inadvertently caused these connection requests to intermittently fail. We've reverted the change and confirmed via internal monitoring that the issue is resolved. Scope of impact: This issue could have potentially affected any of your users intermittently if they were routed through the affected infrastructure.