[Plugin: Yet Another Related Posts Plugin] Related posts not appearing on live post

I don’t understand what is going on with this plugin. I created my latest post:

https://www.milomade.co.uk/blog/2010/04/m20qs-10-cupcake/

And within the post edit screen ‘related posts’ are clearly displayed. When I published the post – no related posts appear. I don’t even get the line of text saying ‘no related posts’ so it must think that there are related posts but not displaying them for some reason.

If I look at the RSS feed – related posts show up there for this post just fine. Why is it that for some posts my related posts won’t show up and on others they will – it seems to pick and mix.

posts with related posts:
https://www.milomade.co.uk/blog/2010/04/make-a-gift-bow-from-a-magazine-page/
https://www.milomade.co.uk/blog/2010/04/200th-fan-giveaway/

posts with related posts that don’t show up:
https://www.milomade.co.uk/blog/2010/04/kinghorn-gets-a-battering/
https://www.milomade.co.uk/blog/2010/03/work-in-progress-vintage-button-earrings/

I’m using the yarpp-template-thumbnail.php template and this is the code within it:

<?php /*
Example template for use with post thumbnails
Requires WordPress 2.9 and a theme which supports post thumbnails
Author: mitcho (Michael Yoshitaka Erlewine)
*/ ?>
<h3>Related Posts</h3>
<?php if ($related_query->have_posts()):?>
<ol class="related-posts">
	<?php while ($related_query->have_posts()) : $related_query->the_post(); ?>
		<?php if (function_exists('has_post_thumbnail')): if (has_post_thumbnail()):?>
		<li><a href="<?php the_permalink() ?>" rel="bookmark" title="<?php the_title_attribute(); ?>"><?php the_post_thumbnail(); ?><br /><?php the_title_attribute(); ?></a></li>
		<?php endif; endif; ?>
	<?php endwhile; ?>
</ol>

<?php else: ?>
<p>No related posts.</p>
<?php endif; ?>

Can anyone help me with this as I’m stumped.