We have opened a support case to Microsoft, but it is still unclear how many users are affected and how long it takes to fix it. We will update this article as needed.
According to latest update by Microsoft, the problem should now be resolved.
It may be necessary to reboot mobile device and/or remove and then add synchronization account again to restore sync.
If your desktop Outlook client does not start normally, it may require the so called Outlook profile to be recreated. Your local ICT-Support can help with this.