Translated version of homepage doesn't show postings of selected categories

Hello, I use WP translation. under https://blog.bissantz.de/?lang=en ther should be displayed (underneath featured content) postings of the category "Bissantz denkt nach" which is properly translated in WP-categories to "Bissantz ponders". But there is an error message. In the german version https://blog.bissantz.de there are displayed all those postings that belong to "Bissantz denkt nach". If I switch in Wordpress admin area to "English" and go then to Design -> Customizer I can select the english Category names to define the category postings on the homepage. But in this case I get the same error on die german Homepage. Could you please help? Thank you in advance. Kind regards Olaf