After successful putting back previous versions, i checked back all differences in all the files. Found out that the problem was created because i used this custom solution: https://support.codeless.co/forums/topic/specular-projects-displayed-without-pagination/. Because it could not be implemented in the child theme (normal way in every other install), it wrote over the customised file in the base-theme when updated of course.
And because the theme has it’s own custom posts, all media is “not attached” to a post, although it does.
