Disableing sensitivity labels for Outlook disabled Client Apps (Word, excel, PPT)

I created two information classification labels in the Security and Compliance Center. "Public" and "Confidential". I published both on the basis of a file and mail policy. Then I downloaded the unified labeling client. At this point everything is fine, the labels appear in the browser, in the client apps and also in outlook.

Then I used the Power Shell Cmdlt  "Shttps://github.com/MicrosoftDocs/Azure-RMSDocs/blob/master/Azure-RMSDocs/rms-client/clientv2-admin-guide-customizations.md#set-a-different-default-label-for-outlook", because I don´t wan´t my mails to be labeled. 

The script works also and my mails are unlabeled. 

 

BUT! After a few hours my client Apps stop to work. I can open all documents in the browser and use sensitivity labels. But as soon as I open them in the client Apps they do not open any more. 

 

Does anybody know this Issue or has an Idea to help?