I believe this issue has been raised before however cannot find the solution.
I have a wordpress plugin called All-in-One Event Calendar Twitter Integration by Time.ly which posts my events to Twitter. The plugin developers indicate that the Card details generated are correct however the majority of the posts do not display the image that is provided from the host website.
The plugin developers indicated that they tested the twitt through the Card Validator which results in ERROR: Internal error (Card error) is
INFO: Page fetched successfully
INFO: 21 metatags were found
INFO: twitter:card = summary tag found
ERROR: Internal error (Card error)
Here is a sample of a failing twit:
Here is one that although the image is displayed in Twitter, the Card Validator still produces the error.
All the twets are suppose to have an image so you can check with any issued from my account.
My Twitter account is macarthurgigs
Thank for your support