Sub items do not appear in Navigation

Hi Pros!

I am trying to add sub-items to my navigation bar so that visitors who hover above an item of my navigation, automatically see the sub-items of that item appearing.

However, when I go to “Appearance”, “Menus” and then move the specific page as a sub item and click “Save menu”, nothing has changed on my website and I still see all the pages as regular items of the navigation bar without any sub-items (of course I tried refreshing the page).

What am I doing wrong? How can I have sub-items within my navigation bar?

Any help is very much appreciated.

Best,
Kilian