Snippet: Custom Listing Post Type Slug

Hello,

I’m trying to use this snippets to change the ‘listing’ post type :

https://docs.wpcasa.com/article/snippet-custom-listing-post-type-slug/

<?php
/**
 * Custom Listing Post Type Slug
 */
add_filter( 'wpsight_rewrite_listings_slug', 'custom_rewrite_listings_slug', 11 );
function custom_rewrite_listings_slug( $slug ) {
	return 'mycustomtype';
}

It works for both new listing i added and the links in the front end are also changed in what i want… But all links bring to 404..

Permalinks seems Ok in both old and new listing i’ve made..

I directly tried to edit the file “class-wpsight-post-types.php”, and changed directly the line 287 :
'rewrite' => array( 'slug' => apply_filters( 'wpsight_rewrite_listings_slug', 'mycustomtype' ), 'with_front' => false ),

But.. It leads to the same result : 404 !

Help appreciated, i really need to change the post type..