This is probably because pages do not include [anspress] shortcode in content. Make sure to add shortcode in every AnsPress page. We have also found that in some themes the post content has been hidden through CSS, probably because theme have some transition effects to show content once page is fully loaded and for reason transition does not work in AnsPress page which results in nothing visible in page.
In rare case, it happens due to error in template override. To find the error you can check error log or by installing query monitor plugin.