When you share a post on Facebook, or when Jetpack Publicize publishes a post to your Facebook page, Facebook crawls the page and looks for Open Graph meta tags in the head to build a complete post preview (with an image, title, description, …).
Jetpack automatically creates these Open Graph Meta tags for you unless you already use another Open Graph plugin, in which case we let the other plugin handle things.
You can see what Facebook sees by entering one of your posts’ URLs in Facebook Debugger:
https://developers.facebook.com/tools/debug
Looking at your site, you’re using the WordPress SEO plugin to handle Open Graph meta tags, so Jetpack doesn’t have control over the look of your posts on Facebook.
WP SEO seems to be adding the tags properly at the moment, so the problem could have 2 different causes:
- The problem happened before you configured the WP SEO plugin, and thus before there were any Open Graph Meta tags on your site. If that’s the case, there shouldn’t be any more problems now.
- When Facebook accessed your site immediately after you published the post, it couldn’t access the post and got a 404 error instead. That could be caused by a caching plugin, or because the first loading time of your posts is too slow.
I hope this clarifies things a bit.