I've just finished installing a new MediaWiki 1.27.0 installation in a Docker container based on Debian Jessie. backed by MariaDB. The extension VisualEditor is installed and works fine. The Wiki is configured to use the German language.
I created a new page and added [[Category:Test]]. I now see the link to the category page but when I follow this link the category-page keeps telling me: "No pages in this category". I also tried [[Kategorie:Test]] but same issue here. Link to the category is visible on this page but the category-page still says "empty".
Any ideas what could be wrong here?