Hi @Solv ,
You can use the Tenant Restrictions view to see which sign in attempts were blocker by the restriction - https://learn.microsoft.com/en-us/azure/active-directory/manage-apps/tenant-restrictions#admin-experience
Based on that information, you would be able to check what type of restrictions are in place and remove them if that's the case.
Let me know if you have any questions or if I'm missing anything.
Thanks