Well from what I see there is no issue here let me explain in detail.
We support Classifieds as we release it and it shows the comment fine Main Index - TMGA Classifieds
Your referring to this page which is your forum and a custom ad block code mod you installed which is not our supported application that we provide support for. Touring Motor Glider Association | TMGA | Online Community for Touring Motor Glider Enthusiasts
Now looking at that page that block shows number of ads and comments for the category that a specific ad is uploaded 2 and your showing the latest 4 ads. The ad that has a comment in your classifieds is not in those results on your block so you should not see any categories with a comment count there. That block has nothing to do with showing comments. It will provide a category count of ads and comments within the category the featured ad is showing from. Therefore if the category does have a comment count it will show a count.