I have a BlackBerry Key2. This is an Android-based phone, but try not to get too caught up in that fact.
I am a consultant for three different companies (each with their own IT admins) and therefore have three different O365 accounts. Two of these are happily connected to my phone and working well using OAuth and MFA. The third one is turning out to be very problematic.
In the two that are working, the admins are able to go into the Azure Active Directory admin center and go to Enterprise applications. They select New application and then search for "blackberry" and the "BlackBerry Hub+ Services application shows (see screen cap below). They are then able to add it, apply the relevant admin permissions (including Active Sync) and I'm able to receive, file, and send email.
In the one that is NOT working, typing "black" (or anything else relevant) into the search function for adding a New application does NOT show the BlackBerry Hub+ Services application.
Can anyone shed light on why this might be the case?