I am to replicate this on an 7+ and Xs Max. When MFA is enabled in additional with MA, same continuously process added with the two-step. When modern authentication is enabled through the O365 tenant the user has to continuously sign in and while trying to sign in the dang pop up of edit settings keeps appearing which confuses users and they click edit again and it starts over, you just have to clear that message an finish entering the password. I thought I would retest and have run into the same thing users are reporting.
Now that Microsoft is updating O365 tenants with modern authentication, iOS users have started to lose access to their mailboxes and a continuous prompt for the password with a very weird process. Maybe Microsoft updated something or Apple did, but it appears to be back with our customers using the native iOS Mail app. For a while there things were working and I have no explanation why. Well, now that I started this thread I get to add to it again.
So if they finally got this to work in the latest release of iOS what is the recommendation? Have all the current users update their passwords in the app from the App Password to their standard password or can we continue to use the App Password? We have noticed the increase in support requests from customers about this issue in the past 2 weeks or less. Has there been recent changes to that platform and the Apple Mail app for iOS? I'm thinking that Apple finally updated the Mail app to support modern authentication, if so why hasn't documentation for it been updated? I can see that Apple introduced the capability in 11.0 but we could not get it to work out of the gate and found it to be NOT 100% reliable. The Mail app then prompts the user to enter their Office 365 password which confuses the end user because they try to re-enter the generated App Password which it then fails to sign in because it actual requires the user's standard password. This should NOT happen if MFA is enabled and an App Password has been created to be used for the Mail app.
When users are out of a known or trusted location and required to MFA to sign in or access Office 365 resources the Apple Mail app for iOS is asking for the user's password. Office 365 MFA and the Apple Mail app for iOS concern? We ourselves and several customers using Office 365 have noticed a recent issue with the Apple Mail app for iOS when Office 365 MFA is enabled.