[Plugin: Sharebar] Post images not showing up on Facebook

When I send a post to facebook, doesn’t matter if I use the Share Button or just copy and paste the article url, images are randomly loaded. I mean that if the articole has an image in it (not necessarily marked as “featured”) sometimes it loads as thumbnail on facebook, sometimes it doesn’t.
If I click on the like button within sharebar it usually works and the image is correctly posted on facebook side by side with the article.

Is there a fix to it? Thanks!

This is a link to a blog post that doesn’t work:
https://www.giacomo.sardelli.name/blog/2012/10/10/the-underwater-realm-5-film-girati-sottacqua/

While this works:
https://www.giacomo.sardelli.name/blog/2012/10/01/cineforum-la-diversita-gran-torino-il-19-ottobre/

https://www.ads-software.com/extend/plugins/sharebar/