As the title says, we noticed today that logging in to the Microsoft Azure mobile app on an iPhone does NOT generate an event in the Azure AD Sign-in logs when the user is authenticating using the Microsoft Authenticator app. When authenticating, the user is redirected to the Microsoft Authenticator app where they select their username, then they are redirected back to the Microsoft Azure app without being prompted for a password or MFA code.
An event is only generated in the Azure AD Sign-in logs if we log in to the Microsoft Azure mobile app or https://portal.azure.com in Safari on an iPhone and authenticate by typing in our username and password and then provide the MFA one-time code.
Why is no event generated in the Sign-in logs in the first scenario when the user is authenticating with the Microsoft Authenticator app?