Images not visible in search results - php

Question

I have this custom search function to search trough custom meta keys in Wordpress. The function works well.
However, all the images that I have added to my post using Advanced Custom Fields are now having their URL's changed to the attachment ID.
This should not happen according to the settings page in ACF:
The same field works ok on other pages, just not on the search results page. Check how it changes the image source on the search results:
How and why is the image URL here changed to the attachment ID? Kindly check out my code below:
function custom_search_function($pieces) {
// filter to select search query
if (is_search() && !is_admin()) {
global $wpdb;
$custom_fields = array('regio','provincie');
$keywords = explode(' ', get_query_var('s'));
$query = "";
foreach ($custom_fields as $field) {
foreach ($keywords as $word) {
$query .= "((mypm1.meta_key = '".$field."')";
$query .= " AND (mypm1.meta_value LIKE '%{$word}%')) OR ";
}
}
if (!empty($query)) {
// add to where clause
$pieces['where'] = str_replace("((({$wpdb->posts}.post_title LIKE '%", "( {$query} (({$wpdb->posts}.post_title LIKE '%", $pieces['where']);
$pieces['join'] = $pieces['join'] . " INNER JOIN {$wpdb->postmeta} AS mypm1 ON ({$wpdb->posts}.ID = mypm1.post_id)";
//$pieces['groupby'] = "{$wpdb->posts}.ID";
}
}
return ($pieces);
}
add_filter('posts_clauses', 'custom_search_function', 20, 1);
EDIT: Here's the code that displays my post results, the "foto" field is the field which is responsible for displaying the image:
<?php foreach( $posts as $post ):
//fusion-column-last, or none for normal class
$lastclass = '';
if(++$counter % 2 === 0) {
$lastclass = ' fusion-column-last';
}
setup_postdata( $post )
?>
<div class="fusion-one-half fusion-layout-column fusion-spacing-yes<?php echo $lastclass?>" style="margin-top:0px;margin-bottom:20px;background-color:white;">
<div class="fusion-column-wrapper">
<div class="bw-search-picture">
<?php $postid = get_the_ID(); ?>
<?php //echo $postid; ?>
<img src="<?php the_field('foto', $postid); ?>" alt="<?php the_title(); ?>"/>
</div>
<div class="bw-search-content">
<h2>
<a class="green" href="<?php the_permalink() ?>" rel="bookmark" title="Permanent Link to <?php the_title_attribute(); ?>"><?php the_title(); ?></a>
</h2>
<p class="bw-regio">Regio <?php the_field('regio'); ?></p>
<p>
<a style="color:#9C9E9F;" href="<?php the_permalink() ?>" rel="bookmark" title="Permanent Link to <?php the_title_attribute(); ?>">LEES VERDER ></a>
</p>
</div>
</div>
</div>
<?php endforeach; ?>

Answer 1

Try for the thumbnail:
$imgsrc = wp_get_attachment_image_src(get_post_thumbnail_id( $post_id ));
echo $imgsrc[0];
Edit, use this code with the attachment id:
$imgsrc = wp_get_attachment_image_src(get_field('foto', $postid));
echo $imgsrc[0];

Answer 2

Rather than using
<img src="<?php the_field('foto', $postid); ?>" />
Try using
<?php $foto_url = get_field('foto', $postid); ?>
<img src="<?php echo $foto_url; ?>" />