Where is your tenant located? Yesterday it was an outage in the South US Datacenter that was affecting Azure AD causing problems when accessing Office 365. I have accessed the portal in one of my tenants, and the health dashboard is reporting there are issues when accessing the Portal...specifically the issue I told at the beginning of my message:
Users may be unable to access or use some features within the Office 365 service.
User Impact: Users may be unable to access or use some features within the Office 365 service.
More info: Users may be intermittently unable to access the Office 365 portal. Additionally, users who are able to access the service may experience the following behaviors:
Exchange – Some users were unable to access Outlook on the web, though service is now restored. Email access through other protocols was unaffected.
Power BI – A subset of users may receive a ‘Server unavailable’ error or may be unable to log in, though our monitoring indicates that availability has recovered. Further details on Power BI can be found under service incident PB147603.
SharePoint – Most impact has been mitigated, but a small subset of users may be unable to make or save changes to SharePoint sites and content. Further details on SharePoint mitigation can be found under service incidents SP147560 and SP147618.
Microsoft Teams – Users may be unable to authenticate or access Office documents within Teams. We're working to verify that this issue is now resolved. Further details on Microsoft Teams can be found under service incident TM147626.
Intune – Affected users may be intermittently unable to access the Intune portal or other functionality. Further details on Microsoft Intune can be found under service incident IT147609.
Education - Affected users may be seeing issues with services including School Data Sync and Assignments within Teams. Further details on School Data Sync can be found under service incident OE147685.
Current status: We're continuing to apply mitigations and our telemetry indicates that availability for the remaining impacted services is improving.
Scope of impact: This issue could potentially affect any of your users who are hosted out of the San Antonio data center. Impact is specific to a subset of users who are served through the affected infrastructure.
Start time: Tuesday, September 4, 2018, at 9:09 AM UTC
Preliminary root cause: Extreme weather in the San Antonio area caused a data center issue, which has affected multiple Office 365 services.
Next update by: Wednesday, September 5, 2018, at 8:00 AM UTC