ACF – Order List Picking order

I have been using your plugin for some time now, I even have the pro version. Everything is great, however I am trying to add items to my picking list (wcol-summary-template).

I created an ACF “Post Object” field in order to attach the name of the linked products (BOM). I would like this to appear just below the meta-data. But impossible to make it appear.

I tried with the_field ('fieldname', $ order-> get_id ()); and the technique given by ACF

<? php
$ featured_posts = get_field ($ summary_item, 'produits_bom');
if ($ featured_posts):?>
<ul>
<? php foreach ($ featured_posts as $ featured_post):
$ permalink = get_permalink ($ featured_post-> ID);
$ title = get_the_title ($ featured_post-> ID);
$ custom_field = get_field ('field_name', $ featured_post-> ID);
?>
<li>
<a href="<?php echo esc_url( $permalink ); ?> "> <? php echo esc_html ($ title); ?> </a>
<span> A custom field from this post: <? php echo esc_html ($ custom_field); ?> </span>
</li>
<? php endforeach; ?>
</ul>
<? php endif; ?>

But nothing appears. Any idea to help me?