We’re having the same problem.
Page validates with image, but about 1-3 minutes later the card just disappears and the tweet shows up once again in the timeline missing the card.
At first I thought it was a safety precaution (for instance if someone changed the actual news site or story to something else), but nothing has changed this time around and it still happens. We’re jusing the “summary” version as we are a news agency and want to provide users with a peak into the story to see if it’s something they care to read the site.
Postscript:
Other users: Are all of the summaries that disappear including images?
Twitter Techs: What happens if someone (either seriously or fecitiously) hits the “report image” button? Would that put the summary “on hold” ? I’m just guessing here but wonder if this problem is in part due to “vandalism”?
Answer to Postscript:
The problem is occuring in summaries without images as well, so the above is not
the possible culprit. This doesn’t rule out people fecitiously marking twitter posts as “spam” if they do not like the message, so that might be something for Twitter techs to check.
Postscript 2:
Other users: Do each of your websites or pages also include Google Microdata metacodes?
Twitter Techs: Could there be some conflict between Google Microdata and Twitter Card metadata?
Postscript 3 (4 hours after summary card disappeared):
Some of our summary cards have reappeared after disappearing without any action
on our part.
