AVAST Premier just showing a blank (white) window

Hi
Suddenly my AVAST Premier just showing a blank (white) window insted of the UI.
Thats a problem and I cannot perform a scan anylonger.
Please let me know how to solve it.

Best regards
Peter

https://support.avast.com/en-eu/article/Repair-Antivirus

There are other reports of this problem. It’s been reported to Avast.