It seems like you are missing a required attribute is missing or not populated for a user. An important thing to consider when setting up provisioning be to review and configure the attribute mappings and workflows that define which user (or group) properties flow from Azure AD to the application. This includes setting the “matching property” that be used to uniquely identify and match users/groups between the two systems.
Check this page for detailed information on setthing up the sync - [https://learn.microsoft.com/en-us/azure/active-directory/app-provisioning/customize-application-attributes
Hope this helps.
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