Hello,
If you please, remove this option from your theme or even remark it as buggy or not working until you fix it.
You can also provide an alternative way that is compatible with your theme.
It have been a long time since occurred and does not seem to be at the top of your list of bugs.
Thank you.

Wow…
I find the solution by myself!!!
I just putted the shortcode inside the field and it worked.
Disclaimer: I was using bad coded shortcode and did not worked the first time.

But to make this topic a little bit useful I am giving you the way I used to insert a single post’s content inside the ad field.
The reason to do such a thing is that it makes it very easy for a non tech user to manage custom ads by simply changing the content of a specific post (adding one linked image).

I just putted this code in the functions.php of the theme:
function show_custom_banner($atts) {
$queried_post = get_post($atts[‘post_id’]);
$content = $queried_post->post_content;
$content = apply_filters(‘the_content’, $content);
$content = str_replace(‘]]>’, ‘]]>’, $content);
return $content;
}
add_shortcode(‘my-banner’, ‘show_custom_banner’);

Then I was able to call any post content wherever I wanted, including the ad fields of your theme:
[my-banner post_id=”1″]

Thank you.