Hello Sakin,
that was the first thing I cheked. I compared single.php to page.php for any differences but there were none. That’s why I don’t get this at all.
I thought I would just add get_sidebar and get_footer lines there and that would be it but sadly, that was not the case.
My single.php file looks like this:
<?php
/**
 * The Template for displaying all single posts
 *
 * @package Catch Themes
 * @subpackage Catch Base
 * @since Catch Base 1.0 
 */
get_header(); ?>
	<main id="main" class="site-main" role="main">
	<?php while ( have_posts() ) : the_post(); ?>
		<?php get_template_part( 'content', 'single' ); ?>
		<?php 
			/** 
			 * catchbase_after_post hook
			 *
			 * @hooked catchbase_post_navigation - 10
			 */
			do_action( 'catchbase_after_post' ); 
			
			/** 
			 * catchbase_comment_section hook
			 *
			 * @hooked catchbase_get_comment_section - 10
			 */
			do_action( 'catchbase_comment_section' ); 
		?>
	<?php endwhile; // end of the loop. ?>
	</main><!-- #main -->
	
<?php get_sidebar(); ?>
<?php get_footer(); ?>
…and I pretty much think it’s exactly the same as the link you posted above.
WHERE’S THE RUG?