Problem with Facebook Thumbnails

Hello all,
I have read a few other posts about Facebook Thumbnails not posting, but they did not solve my problem.

Recently, when I complete a new article and post it to Facebook only a link will show, without any picture (there are pictures in my article). I don’t remember making any drastic changes, what could be the cause of this?

I had it happen once before, but only when “Allow Pings” was not checked. “Allow Pings” is checked now, but still nothing.

Any help troubleshooting through this would be greatly appreciated!

Thanks for your time!
Andy

P.S. If needed I can post a link of the article that I am having trouble with. I have tried others, but the same problem has occurred on all new articles that I make.