Website Image Hidden

Hi guys some of my website result images are hidden, I have thumbnails enabled, and is working great however I notice even though the image exists some are hidden by the display: none class

<div class="mr-3" style="display: none;"> 
		<a class="link d-none d-sm-flex" href="https://*************.com/watch/C9EtEYN39YDlTBn" data-uri="https://*************.com/watch/C9EtEYN39YDlTBn" data-id="aad97a4eec84495ba9b07a4bfab26bca" data-order="1"> <img src="" alt="thumbnail" data-src="/thumbnail/?docId=aad97a4eec84495ba9b07a4bfab26bca&amp;queryId=bad07100046a41b0bdfe56ecf8cd9be7" class="thumbnail" style="background-image: url(&quot;/images/loading.gif&quot;);">

However you can see here the image exists but I notice these images are full URL images and are hidden by the thumbnail class, how can I display these image

Fess checks the min size and max ratio of a thumbnail.
If it does not display, the max ratio is out of the target.
You can modify settings in

Thank you @shinsuke I will modify