Facebook Sharing button doesn’t like verticals!

OK, I’ve just started up on Facebook, Luddite that I am with social media, and I’ve discovered that the Facebook sharing button that appears when you turn that feature on does NOT LIKE VERTICAL images! Here’s what I’m experiencing, and I’ve tested it in IE, FF, and Chrome: If the image is a horizontal, then the thumbnail of the image it is going to share is my header rather than the image, BUT it shows arrow selectors and using those I can select the next image which is the correct thumbnail. Sharing in this manner works correctly. However, if the image is a vertical, again it shows my header in the thumbnail, but it does NOT show the arrow selectors, so I can NOT select the correct image to share. If I share anyway, then the link it shares does point to the right page, but the image it puts with that link in FB is my header, rather than the correct image. It is quite a pain not being able to share verticals, considering so much of my portfolio is waterfalls!

Besides the sharing buttons being turned on, I’ve also got FB connected through JetPack, but don’t have it working, yet (and, by the way, G+ is also not working through JetPack). I’d already heard of problems connecting it through Yoast as well, so I’ve forgone that.

So, any ideas on the sharing button– how to get it to work with verticals?