It was placeholder 137 for wordlist.eu. Right now that modal is not published. I can prepare a test environment, if you think it should have worked by design, but didn't because of some misconfiguration.
Below is exact code which I've used back then. Maybe it was too far in source code and didn't receive any bids?
<div class="modal-dialog" role="document">
<!-- Ezoic - under_first_paragraph x-solve 137 - under_first_paragraph -->
<div id="ezoic-pub-ad-placeholder-137"> </div>
<!-- End Ezoic - under_first_paragraph x-solve 137 - under_first_paragraph -->