Display Post Thumbnail Not Working For Some Posts

Hi there,

“Display post thumbnail” function is not working from some time.
Probably after the last update of the plugin or the last update of the theme.
There are still some thumbnails displayed in the side bar to the right from the older posts.
I’m not using “featured image” in the post, just there is always a first image.

My site’s url is: http://www.cookwithasmile.com

Thanks in advance!

Great plugin btw 🙂

https://ww.wp.xz.cn/plugins/wordpress-popular-posts/