Plugin showing “Also post on Facebook” on only one post

I am having trouble with my Facebook Comments plugin. The “Also post on Facebook” checkbox is only showing on one post: https://www.screencast.com/users/pacecom/folders/Default/media/e4c9220e-584d-46b3-b95a-3f883c22fe5f

The rest of the posts it is showing like this, which does not allow a commenter to post to his/her Facebook account: https://www.screencast.com/users/pacecom/folders/Default/media/d5713752-2a87-4683-bbb1-17ed2a94777a

I have even checked all the settings: https://www.screencast.com/users/pacecom/folders/Default/media/14dcef49-3dd7-404a-936b-925bc7fe762a

Any ideas what may be causing this problem and how I can fix it?

Thanks,
Peter