Shortcode in Featured page content - Catch Kathmandu Pro

function catchkathmandu_featured_content_page( $options ) {
    global $post;
    $quantity       = $options['homepage_featured_qty'];
    $headline       = $options['homepage_featured_headline'];
    $layouts        = $options['homepage_featured_layout'];
    $number_of_post = 0;        // for number of posts
    $post_list      = array();  // list of valid post ids

    $output = '';

    //Get valid number of posts
    for( $i = 1; $i <= $quantity; $i++ ){
        if ( isset ( $options['featured_content_page'][ $i ] ) && $options['featured_content_page'][ $i ] > 0 ) {
            $number_of_post++;

            $post_list  =   array_merge( $post_list, array( $options['featured_content_page'][ $i ] ) );
        }
    }

    //Checking Layout
    if ( 'four-columns' == $layouts  ) {
        $classes = "layout-four";
    }
    else {
        $classes = "layout-three";
    }

    if ( !empty( $post_list ) && $number_of_post > 0 ) {
        $loop = new WP_Query( array(
                    'posts_per_page' => $number_of_post,
                    'post__in'       => $post_list,
                    'orderby'        => 'post__in',
                    'post_type'      => 'page',
                ));

        $i=0;

        $output .= '<section id="featured-post" class="featured-content-page ' . $classes . '">';

        if ( !empty( $headline ) ) {
            $output .= '<h1 id="feature-heading" class="entry-title">' . wp_kses_post( $headline ) . '</h1>';
        }

        $output .= '<div class="featued-content-wrap">';
        while ( $loop->have_posts()) : $loop->the_post(); $i++;
            $title_attribute = the_title_attribute( 'echo=0' );
            $content = get_the_content();
            $output .= '
                <article id="featured-post-' . $i . '" class="post hentry">';
                if ( has_post_thumbnail() ) {
                    $output .= '
                    <figure class="featured-homepage-image">
                        <a href="' . esc_url( get_permalink() ) . '" title="' . $title_attribute . '">
                        '. get_the_post_thumbnail( $post->ID, 'small-featured', array( 'title' => $title_attribute, 'alt' => $title_attribute, 'class' => 'pngfix' ) ) .'
                        </a>
                    </figure>';
                }
                else {
                    $catchkathmandu_first_image = catchkathmandu_get_first_image( $post->ID, 'small-featured', array( 'title' => $title_attribute, 'alt' => $title_attribute, 'class' => 'pngfix' ) );

                    if ( '' != $catchkathmandu_first_image ) {
                        $output .= '
                        <figure class="featured-homepage-image">
                            <a href="' . esc_url( get_permalink() ) . '" title="' . $title_attribute . '">
                                '. $catchkathmandu_first_image .'
                            </a>
                        </figure>';
                    }
                }

                $output .= '
                    <div class="entry-container">';
                        if ( $content !='') {
                            $output .= the_title( '<header class="entry-header"><h1 class="entry-title"><a href="' . esc_url( get_permalink() ) . '" title="' . $title_attribute . '">','</a></h1></header>', false );
                            $output .= '<div class="entry-content">' . do_shortcode( $content ) . '</div>';
                            $output .= '<a href="' . esc_url( get_permalink() ) . '" title="' . $title_attribute . '"></a>';
                        }
                    $output .= '
                    </div><!-- .entry-container -->
                </article><!-- .featured-post-'. $i .' -->';
        endwhile;

        wp_reset_postdata();

        $output .= '</div><!-- .featued-content-wrap -->';

        $output .= '</section><!-- #featured-post -->';
    }

    return $output;
}