terms not linked

Hello, my problem is, that sometimes terms are not linked. If i wrapped them e.g. with maybe strong or span, the term is linked. If the term is not wrapped, the term is not linked. You can see this on the page-link. Click on “Artikel lesen”. At the end of the long article, the penultimate paragraph, you can see the term “Bildungsnetzwerke” two times. First is not linked, second is wrapped with a span and linked. Do you have a hint for me … Plugin is freemium.

The page I need help with: [log in to see the link]