I've started testing the 15.21.1 Office Update and noticed that my Outlook client doesn't seem to authenticate through AD FS/Office 365 with our Office 365 environment thus resulting in the error below:

Reverting back to Outlook 15.19.1 and the authentication works fine again. I tested this on another Mac and the problem occurred there as well.
Tested on El Capitan, 10.11.4.
Does anyone else has this issue as well?

