Outlook 365 screen flashes says “Need password”, but if you click it, you just get a quick blink of a blank windows, and then it disappears.

While the issue is present for the users, it is not possible for them to create a new Outlook profile, as it wouldn’t connect to the mailbox. I had luck with just rebooting my own computer, that fixed the issue for me, but only until the next day. Other users had bigger problems getting it to work.

The issue apparently seems to be an implementation on “Web Account Manager” (WAM) in Office/Windows. The solution is to create the registry key and set the value to 1.

Path: HKEY_CURRENT_USER\Software\Microsoft\Office\16.0\Common\Identity
Key: DisableADALatopWAMOverride (DWORD 32 bit)
Value: 1

No restart required just close Outlook and start it again, enter your password. Done.