I changed theme from a free colormag to newsletter theme from here. But i have a custom template for some categories. When i activate that on the new theme it says no posts.
the core wordpress function have_posts() return false. if i use the standard template, the posts are loaded. Why is that?
But not all posts are missing, and that what is wierd. In some categories there are posts, but not all posts.
Please try to make the theme working at your local pc first. You can try with deactivate your existing plugins to see any plugin is doing conflict with the theme or not.
But for getting best solution contact with your theme Author with your issues screenshots and details explanation