My Portfolio Images are not showing

<?php get_header(); ?>

<?php
/*
Template Name: Portfolio Page
*/
?>

<section class="row">
    <div class="small-12 columns text-center">

    <?php if ( have_posts() ) : while ( have_posts() ) : the_post(); ?>
        <div class="leader">
            <h1><?php the_title(); ?></h1>
            <?php the_content(); ?>
            <?php endwhile; endif; ?>
        </div>
    </div>
</section>

<?php
    $args = array(
    'post_type' => 'portfolio',
    );
    $query = new WP_Query($args);
?>

<section class="row no-max pad">

<?php if ($query->have_posts() ) : while($query->have_posts() ) : $query->the_post(); ?>

        <div class="small-6 medium-4 large-3 columns grid-item">
        <a href="<?php the_permalink(); ?>"><?php the_post_thumbnail('large'); ?></a>
      </div>

      <?php endwhile; endif; wp_reset_postdata(); ?>
</section>


<?php get_footer(); ?>