Hi! I already have read another topic with same problem. But mu situation is a bit different. I have 2 problem with image.
My theme doesnt use featured image, but it use castom field. So i checked "Add Open Graph Tags" and set my "Custom field name:". But ogg:image is the last picture of my post. But this is only the beginning.
Th second problem is selection of picture for facebook. I use post type "Image Post" and "Message text Format:" is %TEXT% %URL%. So your plugin take random picture from my post, not first, not ogg:image.
Could you say me how can i repair it?