[Plugin: WordPress SEO by Yoast] og:image

Using Yoast SEO .latest, this post:

https://credostlouis.org/2011/11/03/institute-for-pastoral-theology-preview-weekend/

seems not to generate a <meta property="og:image" ...> tag even though the post has an image.

I used the Facebook debugger:

https://developers.facebook.com/tools/debug

to see the page source.

I don’t see what I’ve done differently versus any other post. Any ideas?