The problem seems to be that when the Discourse upload markdown is wrapped in HTML tags, the markdown isn’t getting parsed. For example, this is what I’m seeing for a WordPress post after the Discourse PullHotlinkedImages
Job is run:
<small>Originally published at: https://scossar.com/figure-tags-cause-issues/
</small><br>
<figure class="wp-block-image">![](upload://3hPHOMnM5v5srjlz5QWGmVxY4AL.jpeg)</figure>
Editing the post to remove any html tags that are surrounding the markdown link solves the issue, but a proper solution will need to be found for this.