Tree hierachy only shown as an alphabetically ordered list

Unfortunately, I (as a newbie in WP) can’t get the Tree Hierarchy to expand as shown in the example images for this plugin. All pages are just shown alphabetically in a long list under each other so it’s not possible to view Siblings under Parents.

I’m using WP 6.2, a Kadence theme, and Elementor. Any help is very much appreciated.