Featured Image of Post Not Showing Up When made public on Facebook

Have you tried using the Facebook debug tool:
https://developers.facebook.com/tools/debug/

Have you tried disabling all your plugins or using a bundled theme like Twenty Fourteen or Fifteen?

Your top photos are showing and the ones further down aren’t, you’re holding a cup in top and flowers in the other pic, another guy had same issue with Facebook, maybe it’s fb

This is what I get from the fb debugging tool. I don’t understand why.

Critical Errors That Must Be Fixed
Could Not Connect To Server Check that the webserver is running, and that there are no firewalls blocking Facebook’s crawlers.
Warning
Errors That Must Be Fixed
Missing Required PropertyThe ‘og:type’ property is required, but not present.

Could Not Connect To Server Check that the webserver is running

This is what worries me most, I think. Have you tried contacting your hosting provider? It may be a server issue or server setup going nutty and not the smooth spreadable type.

What steps have you tried in order to resolve this? Deactivating plugins, switching themes?

I am having similar issues – the featured image would displayed correctly a couple of weeks ago (9/16) for all posts. The last two posts we added to the site have the header image displayed with the Facebook post even though there is a designated featured image.
https://www.gaviidaesails.com
https://www.facebook.com/Gaviidae-Sails-1664632877104253

I am having similar issues – the featured image would displayed correctly a couple of weeks ago (9/16) for all posts. The last two posts we added to the site have the header image displayed with the Facebook post even though there is a designated featured image.
https://www.gaviidaesails.com
https://www.facebook.com/Gaviidae-Sails-1664632877104253