Wordpress custom post type in archive list
//show custom post type in archives.
function ns_set_archive_post_types($query){
// We cannot use 'is_archive' here because post type archives should not be included
$is_target_query =
!is_admin() &&
$query->is_main_query() &&
($query->is_date ||
$query->is_author ||
$query->is_category ||
$query->is_tag ||
$query->is_tax);
if($is_target_query){
$target_types = array('post', 'ns_book_cpt');
$query->set('post_type', $target_types);
}
}
add_action('pre_get_posts', 'ns_set_archive_post_types', 10, 1);
ref:https://www.rafaelcardero.com/courses/post-types-in-wordpress/l/109/