Can’t change featured image

Hi, I get time to time post made by Aiomatic that has an unchangeable featured image. After changes and republishing the post, I can find this code that pulls an image (found originally by Aiomatic)  that overrides the new, changed featured image. Example: <div class="entry-header"><div class="nv-title-meta-wrap"> <div class="nv-thumb-wrap"><img src="https://upload.wikimedia.org/wikipedia/commons/d/d3/Grand-Hype_%28Revamp%29.jpg" alt="post thumbnail"></div> I regenerated my image/post thumbs, didn't help, and changed featured images and text details/attachments, etc., without help. How to prevent this and correct published posts?