WordPress, by default, shows only posts on tags and categories archives… So if you want to show your custom post type in there, then you’ll have to make WordPress do that…
function add_news_articles_to_categories_and_tags( $query ) {
if ( ! is_admin() && $query->is_main_query() && ($query->is_category || $query->is_tax ) ) {
$query->set( 'post_type', array('post', 'news_article') ); // use your CPT slugs in here
}
}
add_action( 'pre_get_posts', 'add_news_articles_to_categories_and_tags' );