Bring only posts that are from specific id's

Hey

I want to build an option where in every single-post, there are 3 “realted posts” at the bottom of it.
So I put this code in the bottom of “content-single.php”:

<div class="related-posts">
		$args = array(

				'post__in'      => array(38328, 38359, 323213)
		);
		$the_posts = new WP_Query($args);
		//if ( $the_posts ){
		echo '<div class="row">';
		while ($the_posts->have_posts()): $the_posts->the_post();?>

			<div class="col-sm-4">
				<?php
				if (has_post_thumbnail()):
					the_post_thumbnail();
				endif;
				?>
				<?php the_title() . '<br/>'; ?>
			</div>

		<?php endwhile;
		echo '</div>';
		//}
		wp_reset_postdata();

		var_dump($the_posts);
		//var_dump($the_query);

		else:
			echo"no related posts found";
	endif;
	?>
</div>

But in one post, I get 8 different posts, and in other post I get no posts at all, although I chose only three posts in “post__in”.
Any idea why that’s happening and how I can make it done?

Thanks in advance!