Outlook2016 keeps asking for password for outlook.com-Account after Parallels Update to 15.1.4.

Hello,

after the Parallels Update to 15.1.4 my Outlook 2016 keeps asking for the Password to my outlook.com account.
If I enter it wrongly, it states that it is not correct. If I enter it correctly, the password window closes and opens up again in seconds.
The other accounts (web.de, private Server etc.) work fine. Calendar of that account also works fine (of course it does not sync).
Anyone else seen this behaviour and found a solution?
Already tried:
No change in behaviour after deleting all outlook-related credentials in the credential manager
Same behaviour if a create a new account with the same name

Best!
Timm