Show Custom Taxonomy Inside Custom Menu

I have a custom menu using add_menu_page:

add_menu_page('My menu' , 'Some text', 'read', 'nwcm');

Under it, I show a custom post type menu item;

// Create the news custom post type
register_post_type('nwcm_news', array(
    'labels' => array(
        'name' => __('News for clients', NWCM_TEXT_DOMAIN) ,
        'singular_name' => __('News', NWCM_TEXT_DOMAIN)
    ) ,
    'public' => true,
    'has_archive' => true,
    'public' => true,
    'show_ui' => true,
    'show_in_menu' => 'nwcm',
    'taxonomies' => array(
        'nwcm_news_category'
    ) ,
));

Then I add a custom taxonomy hooked to that “nwcm_news” post type:

// register news taxonomy
register_taxonomy('nwcm_news_category', 'nwcm_news', array(
    'label' => __('News categories') ,
    'menu_name' => __('News categories') ,
    'rewrite' => array(
        'slug' => 'nwcm_news_category'
    ) ,
    'hierarchical' => true
));

The parent menu and the custom post type both show correctly… but, the taxonomy menu isn’t showing 🙁

How can I solve this? I had checked this solution but the answer lacks the full code example..