Sort posts by ACF date field

I have created a ne wpost type named “shows”, and assigned an ACF date field to it. While succeeding in displaying the posts and their details – I’m failing to sort them by date (the ACF date, not the post creation date).

Here is my code: http://codeshare.io/rpZIL

<ul id="shows-container">
    <?php
    $today = current_time('Ymd');
    $args = array(
        'post_type' => 'shows',
        'post_status' => 'publish',
        'meta_query' => array(
            array(
                'key'       => 'show_date',
                'compare'   => '>=',
                'value'     => $today,
            )
            ),
        'meta_key'          => 'show_date',
        'orderby'           => 'meta_value_num',
        'order'             => 'ASC'
    );
    //the query
    $theshows = new WP_Query($args);

    if($theshows->have_posts()):
        while($theshows->have_posts()):
            $theshows->the_post();
            $showdate = get_field('show_date');
            $showday = get_field('show_day');
            $showhour = get_field('show_time');
            $showloc = get_field('show_location');
            $showphone = get_field('show_phone');
            $showtickets = get_field('show_tickets');
    ?>

        <li class="show-box">
            <h3><?php the_title() ?></h3>
            <div class="show-time">
                <span class="show-date"><? echo $showdate ?></span>-<span class="show-day"><? echo $showday ?></span>-<span class="show-hour"><? echo $showhour ?></span>
            </div>
            <p class="show-address"><? echo $showloc ?></p>
            <p class="show-phone"><? echo $showphone ?></p>
            <a href="<? echo $showtickets ?>"><span><?php _e('Tickets','doliart');?></span></a>
        </li>

        <?php
        endwhile;
    else:
        ?>

        Oops, there are no posts.

    <?php
    endif;

     wp_reset_query(); ?>
</ul>