We have our Twitter Card validated and approved a little while ago. Most of the time it works like a charm, but sometimes it seems to fail, and I don’t understand why this is.
Here’s an example of a working one: https://twitter.com/DjGracha/status/450966746099642368
Here’s an example of a tweet that doesn’t show the card: https://twitter.com/Chris_Goddard/status/450741241320583168
When trying to validate the url’s in these tweets, both validate just fine. So I’m not quite sure why some don’t seem to work.