title: Categories and Post Tags are disable when adding custom post
body: <p>I am working on a wordpress plugin. I have create a custom post type and created two user role for createing and editing the post type. But the problem is when I want to create a new post of my custom post type it shows the Category and Post Tag, but check boxes, text area inside Category and Post Tag meta boxes are disabled. </p>
  
  <pre><code>private function _cpCreateCustomPostType(){
      $labels = array(
              'name' =&gt; __( 'Custom Posts' ), //- general name for the post type, usually plural. The same as, and overridden by $post_type_object-&gt;label
              'singular_name' =&gt; __( 'Custom Post' ), //- name for one object of this post type. Defaults to value of name
              'menu_name' =&gt; __( 'Custom Post Menu Name' ), //- the menu name text. This string is the name to give menu items. Defaults to value of name
              'all_items' =&gt; __( 'Custom Post All Items' ), //- the all items text used in the menu. Default is the Name label
              'add_new' =&gt; __('Add New','Custom Post'), //- the add new text. The default is Add New for both hierarchical and non-hierarchical types. When internationalizing this string, please use a gettext context matching your post type. Example: _x('Add New', 'product');
              'add_new_item' =&gt; __( 'Add New Post/Add New Page (Custom Post)' ), //- the add new item text. Default is Add New Post/Add New Page
              'edit_item' =&gt; __( 'Edit Post/Edit Page (Custom Post)' ),  //- the edit item text. Default is Edit Post/Edit Page
              'new_item' =&gt; __( 'New Post/New Page (Custom Post)' ), //- the new item text. Default is New Post/New Page
              'view_item' =&gt; __( 'View Post/View Page (Custom Post)' ), //- the view item text. Default is View Post/View Page
              'search_items' =&gt; __( 'Search Posts/Search Pages (Custom Post)' ), //- the search items text. Default is Search Posts/Search Pages
              'not_found' =&gt; __( 'No posts found/No pages found (Custom Post)' ), //- the not found text. Default is No posts found/No pages found
              'not_found_in_trash' =&gt; __( 'No posts found in Trash/No pages found in Trash (Custom Post)' ), //- the not found in trash text. Default is No posts found in Trash/No pages found in Trash
              'parent_item_colon' =&gt; __( 'Parent Page (Custom Post)' ) //- the parent text. This string isn't used on non-hierarchical types. In hierarchical ones the default is Parent Page
      );
      $args = array(
              'labels' =&gt; $labels,
              'public' =&gt; true,
              'menu_position' =&gt; 15,
              'capability_type' =&gt; 'custom_post',
              'map_meta_cap' =&gt; true,
              'supports' =&gt; array( 'title', 'editor', 'comments' ),
              'taxonomies' =&gt; array( 'category', 'post_tag' ),
              'has_archive' =&gt; false
      );
  
      if(!post_type_exists('custom_post')){
          register_post_type('custom_post',$args);
      }
      register_taxonomy_for_object_type('category', 'custom_post');
      register_taxonomy_for_object_type('post_tag', 'custom_post');
  }
      private function _cpAddRoles() {
      add_role('cp_author', 'Custom Post Author', array(
      'edit_custom_posts' =&gt; true,
      'read' =&gt; true, // True allows that capability
      ));
  
      add_role('cp_editor', 'Custom Post Editor', array(
      'edit_custom_posts' =&gt; true,
      'read' =&gt; true, // True allows that capability
      ));
  }
  </code></pre>