@Martin yes, that icon. Previous to 1.7, after editing a post with attachment, the icon is gone.
<p>For archiving reasons, i'm attaching the latest version here (1.0.4 ).</p>
<p> </p>
<div id="wpfa-" class="wpforo-attached-file"><a class="wpforo-default-attachment" href="//www.domain.com/wp-content/uploads/wpforo/default_attachments/1565374552-renew_ads_104.zip" target="_blank" rel="noopener"> renew_ads_104.zip</a></div>
Ok, all is clear. As you may notice the new version of wpForo Advanced Attachment addon inserts image thumbnails and files icons directly in editors. So the file icons already exist in database. But old files were just shortcodes [ attach ] 44 [ / attach ] without icons. Those icons were added to files on displaying process. Now it's not necessary because all icons are already added in database on post creation process. And this function is disabled, that's why the old attachments icons are not being added. Please wait for the update, I hope this can be fixed soon.
Ok, then could you check the content of this post in database? Find the PostID, go to phpMyAdmin > Database, search in wp_wpforo_posts table and copy the body field data and paste it here.