Hello Daniel,
The issue appears to be with the initial request made by Adaxes when obtaining account properties. For some reason specific account properties were not returned by Azure AD correctly and the situation you face occurs. We were not able to reproduce the behavior and cannot even tell whether the root cause of the issue is in Adaxes or on the Microsoft side. As of now, we recommend trying to unregister your Azure AD domain in Adaxes and then register it again.
Should the issue persist, please, send us (support@adaxes.com) a copy of the Adaxes Event Log in EVTX format. For information on how to view the log, have a look at the following help article: https://www.adaxes.com/help/ServiceEventLog.