For EVERYONE having this issue, I recommend installing -
http://wordpress.org/plugins/wp-facebook-open-graph-protocol/
This will overwrite the Jetpack OG META TAGS and fix the issue of not selecting your featured image when posting to Facebook.
This plugin has the MISSING Meta Tag OG_IMAGE included and this is why it works and Jetpack doesn't..... As you CAN SEE BELOW....
Raw Open Graph Document Information
Meta Tag <meta property="fb:admins" content="**************" />
Meta Tag <meta property="fb:app_id" content="*****************" />
Meta Tag <meta property="og:url" content="http://thecrewenews.co.uk" />
Meta Tag <meta property="og:title" content="The Crewe News" />
Meta Tag <meta property="og:site_name" content="The Crewe News" />
Meta Tag <meta property="og:description" content="Bringing you all the latest Community & Charity News from around our area" />
Meta Tag <meta property="og:type" content="website" />
Meta Tag <meta property="og:image" content="http://thecrewenews.co.uk/wp-content/uploads/Crewe-News-logo-with-banner1.jpg" />
Meta Tag <meta property="og:locale" content="en_us" />
Thank you jetpack for over seeing this vital error.
Now go fix it :)