Between 0930h and 1800h UTC, A very small set of Azure AD B2C Directory administrators experienced intermittent failures accessing the Azure AD B2C blades and some end-users had intermittent failed authentications. Users who retried, were likely able to authenticate and access the protected resources. The issue has been mitigated.
Only a few B2C tenants were impacted with small impact to end users.
We apologize for the inconvenience. If you have any additional insights/repro, please communicate with us on AADB2CPreview@microsoft.com.
Reference: https://azure.microsoft.com/en-us/status/