No pictures/thumbnails

Operating System: Windows 10

Lightroom Version: 7

I tried today the new lightroom classic. Since i installed it i can't see any pictures/thumbnails in the library or when i import pictures. In the develop module i can see the pictures/thumbnails. How can i solve this problem?

https://www.dropbox.com/s/ffsk5p7yxfnrsr9/21-10-_2017_00-33-24.png?dl=0

https://www.dropbox.com/s/x3czf1msnbogii0/21-10-_2017_00-51-03.png?dl=0