thumbnail image not loading only sometimes

[rocaiguina]

hey @benlk
I am seeing an issue in the production site, but am being unable to reproduce it locally.
Hopefully you can give me a hint of what could be happening.

Sometimes, I haven't been able to track the condition, the thumbnail image doesn't load.
For example here: http://periodismoinvestigativo.com/series/islands-adrift/
Locally it always does. I have tried different images including an image that display in another post. Haven't been able to get it working.

This is the code

umbrella-cpipr/wp-content/themes/cpipr/partials/content-series.php

Lines 41 to 53 in 6f6a99a

	<div class="span6 mobile-no-offset item-article" id="post-<?php the_ID(); ?>">
	<a href="<?php echo get_permalink(); ?>">
	<div class="wrapper-image">
	<?php if ( $show_thumbnail ) {
	echo get_the_post_thumbnail(null, $size = ('rect_thumb'), $attr = '');
	}?>
	<div class="title-article">
	<h2><?php the_title(); ?></h2>
	<p class="date-text"><?php the_time('j F, Y') ?></p>
	</div>
	</div>
	</a>

[rocaiguina]

found it