we have our own on-premise exchange infrastructure and need to prevent using o365 accounts in Office / Outlook 2016.
Therefore we have configured the follow GPO "Block Signing into Office" with "None allowed". That had worked for the last times.
Since view weeks, it does not works anymore and every user can add a third-party O365 account to our Office suite.
The GPO are applied and the reg value are correct.
Are there any known changes by MS in Windows, Office or GPOs that have changed the behavior?
What can I do, to block the O365 cloud features on my devices?
We are running Windows 10 Enterprise v1809 and Office 2016.