Articles not shown in categories

I updated to 2.8 on sunday, and now i have the following problem:

some of the articles aren’t shown in the categories. I have about ~ 250 articles in the category “general”, the articles themself are viewable, but once i click on “general” to filter only the posts in general there are only 4 posts.

This problem is only with the general category, all others work without any problems.