Related Posts not work

I have function:

function ep_get_related_posts($post_id = null, $related_post_count = 5)
{
	if (class_exists('\ElasticPress\Features')) {
		$related_posts = \ElasticPress\Features::factory()->get_registered_feature('related_posts')->find_related($post_id, $related_post_count);

		if ($related_posts) {
			echo '<h2>Похожие новости:</h2>';
			echo '<ul>';
			foreach ($related_posts as $related_post) {
				echo '<li><a href="' . get_permalink($related_post->ID) . '">' . $related_post->post_title . '</a></li>';
			}
			echo '</ul>';
		} else {
			echo 'No related posts found.';
		}
	} else {
		echo 'ElasticPress is not available.';
	}
}

When inserting into news (I have about 300k of them, news portal) I get “No related posts found”. Through the block in Gutenberg I get the same thing.