The version 1.1.11 does not generate the og:image meta tag at all (though the post does have an image). As a result, often the first image on the site is taken as the post thumbnail, which is the site header (which is quite wrong).
The debugger info executed on such a page states:
The 'og:image' property should be explicitly provided, even if a value can be inferred from other tags.
All the images referenced by og:image should be at least 200px in both dimensions. Please check all the images with tag og:image in the given url and ensure that it meets the recommended specification.