Graph API not finding phone number

Question

Hi,

When a user enters their phone number in multi-factor authentication the /authentication/phoneMethods graph API is unable to retrieve it until it has been changed to a username. This can only be done by logging into azure and changing the phone number manually

Why is the portal /authentication/phoneMethods API unable to find this phone number when it is clearly displayed within the Authentication methods submenu in Azure. Is there anything which can be done to automatically make the phone number a username (when entered via multi-factor authentication)?

Thanks,
Josih