NO search results after adding additional info into index

I use Ivory search to search in WooCommerce products. I want to add some fields created with Carbon Fields into search index. Because all of them are private meta fields i decided to add content of this field into post content via hook.

So i added this function:

add_filter('is_index_post_content', 'crb_add_field_to_search', 10, 2);

function crb_add_field_to_search($to_index, $post): string
{
$to_index .= carbon_get_post_meta($post->ID, 'crb_long_name');
return $to_index;
}

After creating index i can see words from this field in wp_is_inverted_index table. I can find them assosiated with desired product. But search results doesn’t show.