Here is the affected site
and the twitter feed
As can be seen in that feed, Blogposts from before Nov 11 2013 are correctly rendered as Twitter cards.
But posts from after that date are not.
Nothing has changed on this side.
Note that it’s wordress.com, not wordpress.org, which means that the blog is fully hosted on wordpress and that they insert the Twitter Card meta tags automatically. Have checked HTML source for before and after, and the Twitter Card content is unchanged.
Finally, the Twitter Card validator says that everything is valid, and even renders the non-operational blogpost correctly.
Please advise as it does not look like a problem that can be fixed on our side.
thanks & regards