One Pager Include Template Part

Good morning everyone and happy 2017

May all your wishes come true !

Question: how to include a short-code <?php echo do_shortcode("[shortcode]"); ?> within the DIV of a One-Page-Design?

Situation: I have a multi-div One-Page design which is the front-page.php. It works fine with CPT's and such, but when I try to add a short-code for Appointments+, e.g. [app_monthly_schedule], it isn't working. Investigating the generated html reveals that an empty div is created. No errors or warnings are shown.

Code used:
1. I created a template-page, called agenda, with the following code in the body:

<div class="container">____WP_END_HEADER____
    <div class="row">
        <?php if ( have_posts() ) : ?>
            <?php while ( have_posts() ) : the_post(); ?>
                <div class="col-md-10 col-md-offset-1 text-center">
                    <?php the_content(); ?>
                    <h3><?php _e( 'Column title', 'twentyfourdegreesonepage' ); ?></h3>
                    <p><?php _e( 'Cras justo odio, dapibus ac facilisis in, egestas eget quam. Donec id elit non mi porta gravida at eget metus. Nullam id dolor id nibh ultricies vehicula ut id elit.', 'twentyfourdegreesonepage' ); ?></p>
            <?php endwhile; ?>
        <?php else : ?>
            <p><?php _e( 'Sorry, no posts matched your criteria.', 'twentyfourdegreesonepage' ); ?></p>
        <?php endif; ?>
    </div>    ____WP_START_FOOTER____

2. From the respective DIV, I call the template using the following code:

<div class="col-xs-12 bg-content">
        <?php get_template_part( 'agenda', 'Agenda' ); ?>
    <h1><?php _e( 'Agenda', 'twentyfourdegreesonepage' ); ?></h1>
    <p><?php _e( 'Bla bla bla text', 'twentyfourdegreesonepage' ); ?></p>

Although I'm a beginner I still think this is the way it should be done. But for some odd reason, it isn't working.

I'll set up a test server right now and will open it for support.

Thanks for all the help and suggestions!