ACF custom loop shortcode

Hi,

I’m using ACF PlugIn for custom events. What I want is to show future events with the help of a shortcode inside the Avia builder. Unfortunately the loop is always shown at the beginning of the page, not at the position of the shortcode. What am I doing wrong?

<?php

/* -------------------------------------------------------------
	SHORTCODE FUTURE EVENTS
------------------------------------------------------------- */

function future_events_all_shortcode() {

// Begin Function

$today = current_time('Y-m-d');
$args = array(
    'post_type' => 'veranstaltungen',
    'posts_per_page' => '20',
    'meta_key'  => 'datum_beginn',
    'order' => 'ASC',
    'orderby' => 'meta_value',
    'meta_query' => array(
      array(
            'key'   => 'datum_beginn',
            'compare' => '>=',
            'value'   => $today,
        	'type' => 'DATETIME'
        ),
    ),
);

// Format date
$date = get_field('datum_beginn');
$date_day = date_i18n("D", strtotime($date));
$date_day_digit = date_i18n("d", strtotime($date));
$date_month = date_i18n("M", strtotime($date));

 
$children = new WP_Query($args);

if ($children->have_posts()) :
	while ($children->have_posts()) : $children->the_post(); $fields = (object) get_fields();
    
    echo '<div class="atomic-events">';
	    
	    echo '<div class="atomic-event">';
	    	
	    	echo '<div class="event-date">';
				echo '<div class="event-date-day">', $date_day, '</div>';
				echo '<div class="event-date-day-digit">', $date_day_digit, '</div>';
				echo '<div class="event-date-month">', $date_month, '</div>';
			echo '</div>'; // end event-date
			
			echo '<div class="event-text">';			
				echo '<h1 class="event-title"><a href="' , the_permalink() , '">' , the_title() , '</a></h1>';
			echo '</div">'; // end event text
			
			echo '<div class="event-image">';			
				echo '<div class="event-image"><a href="' , the_permalink() , '">' , the_post_thumbnail( 'large', array( 'class' => 'img-responsive' ) ) , '</a></div>';
			echo '</div">'; // end event image
			
	    echo '</div>'; // end event
	
	echo '</div>'; // end events
	
 	endwhile; wp_reset_postdata();
endif;

// End Function

}
add_shortcode('future_events', 'future_events_all_shortcode');