Sorry for silly question, but I can’t find out why there are no products listed on category pages although there are products published and in stock in such category. Check this for example: https://gruen.haus/kategoria-produktu/sun-shades/screens/
Product category is the Woocommerce functionality and our theme does not influence that.
Please make the full backup of your site and check the issue on the Storefront theme to detect if our theme causes the problem. Storefront is a free theme developed by WooСommerce.
Here is the woocommerce documentation: https://woocommerce.com/document/managing-product-taxonomies/