We are facing constant problems with the desktop apps in O365, wheter it’s RDS servers that somehow are Azure joined by a user from login 1001 errors to modern authentication Windows that automatically disappear or other generic error 1001 logon bullshit. We have a tome of registry bullshit with shit like EnableADAL to deleting the AAD appx folder from the user profile and/or reinstalling it through Powershell and so it goes on… usually dicking around with these settings will make it magically work for a few weeks…
The amount of time this costs us and our customers is truly staggering, are we the only shop facing this?
With 70k users we do see problems from time to time, but nothing too the level I would call it problematic.