Post templates not working

The post templates do not seem to be working. The default Zeever child “Posts” and “Single post” templates do not work; also tried to create a custom template for all blog posts, and single blog posts (the same format). But posts either cannot select the template (if template is designed for all or single posts/pages – can only select template if template is a “general design”. Otherwise the post page when viewing is blank – showing only header and footer.

Is there a workaround for this?