Remove custom post type slug from permalinks 2

remove-custom-post-type-slug-from-permalinks-2.php

<?php

/**
 * Have WordPress match postname to any of our public post types (post, page, race).
 * All of our public post types can have /post-name/ as the slug, so they need to be unique across all posts.
 * By default, WordPress only accounts for posts and pages where the slug is /post-name/.
 *
 * @param $query The current query.
 */
function gp_add_cpt_post_names_to_main_query( $query ) {

	// Bail if this is not the main query.
	if ( ! $query->is_main_query() ) {
		return;
	}

	// Bail if this query doesn't match our very specific rewrite rule.
	if ( ! isset( $query->query['page'] ) || 2 !== count( $query->query ) ) {
		return;
	}

	// Bail if we're not querying based on the post name.
	if ( empty( $query->query['name'] ) ) {
		return;
	}

	// Add CPT to the list of post types WP will include when it queries based on the post name.
	$query->set( 'post_type', array( 'post', 'page', 'race' ) );
}
add_action( 'pre_get_posts', 'gp_add_cpt_post_names_to_main_query' );

The code works for Parent Pages but for the child pages.
I am trying to remove the word 'slug' here

domain.com/slug/hosting (works)
domain.com/slug/hosting/wp-engine (getting 404 error)

My CPT is hierachical where the second links is the child of the first link. I am getting 404 error for the second.

code does not work.