Category Listing does not show original price with discounts

-- url of the page with the problem -- : die-besten-weine-der-welt.de/DE/angebote
-- HikaShop version -- : 3.1.1
-- Joomla version -- : 3.7.2

Hi, I used to have one product discounted (since a year or so). This correctly diplays in the category listing AND in the product details page the original price (Strikethrough) and the new reduced price.

When adding new discounted products now, those new products show only in the produchttp://die-besten-weine-der-welt.de/DE/angebotet details page both prices. On the category listing page only the discounted price appears. However for the "old" product everything remains correct with both prices on both pages. To see the effect, use above link to the category.

Anyone any idea what is going wrong?