add_featured_meta_box

mZoo · September 14, 2015, 3:05am

You need to add the namespace when you reference the callback in register_post_assets:

function register_post_assets(){
    add_meta_box('featured-post', __('Featured Post'), __NAMESPACE__ . '\\add_featured_meta_box', 'post', 'advanced', 'high');
}
add_action('admin_init', __NAMESPACE__ . '\\register_post_assets', 1);