I found the solution to my problem on page 17 of the Tyche topics:
New category not showing in widget “Tyche Products”
My category name was not identical to the slug name. This because my site is a swiss site. And as you may know, Switzerland has 4 official languages (German, French, Italien and Romantsch) and it is pretty normal that sites are at least in two of those 4 languages. Very often also in English.
Now this leads me to a new problem: When category name and slug name have to be the same, how will it be possible for the content widget to display the products in the correct language? E.g. for displaying the category “Topsellers” in German the slug name was “de-topsellers” and for French “fr-topsellers”. But when the slug name has to be “topsellers” too, how to make sure the product with the right language will be displayed?
Any suggestions?