Unable to close XD, Buggy library and undo doesn't work in XD 50 version on windows

Hi,

Adobe XD seems to be completely broken. I have the following issues:

1. I can't add elements from the CC library anymore, all I can do is to add a copy - if I select "place copy" ("Kopie platzieren" in German), XD sometimes crashes, sometimes adds the asset but usually loses it later on
2. Sometimes I can't undo changes. The option is greyed out in the menu and entering ctrl + z has no effect
3. I often can't close XD (especcially when it starts to behave strange).
4. Sometimes I can't copy elements within the document.
5. Navigation through the library does not work sometimes. This means I cant switch from the document library to a cc library, for example (see screenshot) and if I click on the Icon to publish as a library XD the new window crashes (XD itself is running but the windows stays in front).
   

    

6. CC preview images stop working for recently changed elements. There no longer are thumnails, instead a Adobe Cloud icon is displayed. 
   

I'm using XD 50.0.12 on Windows 10 (latest drivers installed) und a Surface Book 3.

I deinstalled an reinstalled XD - no effect.

Thank you in advance
Sven

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