Yes, it would appear so.
However they do work on all or other domains, so we can derive that the issue is content based. And here’s the culprit, </span>.
You could argue that the omission of a </span> tag amounts to sloppy coding which is fair enough, but really it’s not the end of the world is it? In the order of things we’re not going to lose our Google rankings, burn the server centre down or face a firing squad are we?
As always Firefox came to the rescue, easily pointing out the issue by highlighting the closing </p> parent tag in code view.