starson02

The error is in the line
if(strpos( $url, home_url() ) === false) return false;
because $url of the image is /siteurl/uploads/… and home_url() is /siteurl/ + ‘language’

The image should be shown on the category page (content.php) not content-single.php.

Please compare pages in English and other language:
http://test.trophyclub.ca/category/related/
http://test.trophyclub.ca/de/category/related/

		<div class="post-img">
				<?php
					$thumb = get_post_thumbnail_id();
					$img_url = wp_get_attachment_url( $thumb,'full' ); //get full URL to image (use "large" or "medium" if the images too big)
					$image = aq_resize( $img_url, 300, 300, true ); //resize & crop the image
				?>
				
				<?php if($image) : ?>
					<a href="<?php the_permalink(); ?>"><img src="<?php echo $image ?>"/></a>
				<?php endif; ?>
		</div>