Theme redirects ajax requests for users that are not logged in

SOLUTION: the theme was using an ‘init’ hook to protect its admin area, but this was also redirecting anonymous ajax requests. When I can find a safe way to disable this without compromising the admin area I will post.

// stop users accessing the admin
add_action('init', array( $this, 'prevent_admin_access' ), 0);

function prevent_admin_access() {       

    if (strpos(strtolower($_SERVER['REQUEST_URI']), '/wp-admin') !== false) {
        $current_user = wp_get_current_user(); 

        if(!user_can($current_user->ID, 'administrator') && ( !user_can($current_user->ID, 'contributor') ) ){
            wp_redirect(get_option('siteurl'));
        }
    }
}

The author of Classifieds Theme updated the theme to patch the problem. Are you experiencing a similar problem?

Well the “patch” is to not highjack the ajax requests like this theme was doing. I imagine he just found a better way to protect his admin area. I can’t really suggest a fix though, since in this theme all you would need to do is remove the hook noted above.
I would recommend searching for add_action('init' or /wp-admin in your theme to see if it’s the same problem, if yes, decide how else to do whatever those lines are doing instead of just wholesale blocking access to the admin files of WP.