I had this problem, managed to fix it, now with the jetpack update I just installed Wednesday, the problem has returned. The wrong image is being sent to FB, even though I have a featured image set, and the image size is 200x200 minimum (most of the time I do 225x300 - learned this was the cause of the previous problem of wrong images going to Facebook). I see no obvious reason why this is suddenly happening again. I have not made another changes or updates to WP, FB or any plugins.
I am 100% positive the problem surfaced after I did the JetPack update though...everything was working like clockwork until Wednesday morning after the update.
I would also note that when I go to the post on FB and use the Facebook share button from the post, the image works fine and appears correctly on FB unlike the last time I had this problem.