Hello, @Oliver Theiß,
It is nothing but a cache issue. because when I log in to your site it is working fine for me as you can see in this image: https://postimg.cc/WdpQH8S1 I can see that you are using multiple cache plugins like “Assets clean up, and breeze” Please first disable the cache plugins and then contact your service provider to flush the server cache completely then check back to your site after clearing the browser cache.
Regards 8Themes Team.
One standard license is valid only for 1 project. Running multiple projects on a single license is a copyright violation.