Image Advanced Error

Hi,

Image Advanced is rendering, but is producing the following error (from the source code):

<div style='float:left'>
        <br />
<b>Warning</b>:  Invalid argument supplied for foreach() in <b>/home/michae05/public_html/wholeprophesie/wp-content/plugins/meta-box/inc/fields/fieldset-text.php</b> on line <b>119</b><br />
        <img src="https://www.michaelriordan.co.uk/wholeprophesie/wp-content/uploads/2020/06/1603-3-202x300.gif" style="margin-left:15%;margin-top:5%"></img>
            </div>

Code that produces this:

<div style='float:left'>
        {% for item in post.image_upload_kbuw6hblq1 %}
        <img src="{{ item.medium.url }}" style="margin-left:15%;margin-top:5%"></img>
        {% endfor %}
    </div>

Why is the error appearing?