We have Twitter Summary Card approval for our domain, and it is working in some instances, but not others. Both URLs are “green lighted”, approved and show correctly when plugged into the validator @ https://dev.twitter.com/docs/cards/validation/validator
For example, this URL will correctly Tweet the Twitter Card Summary: http://uat.legacy.com/guestbooks/chicagotribune/guestbook.aspx?n=gail-mahoney&pid=21109&view=3&entry=39672654#sthash.obb3KkKD.WSfw5SQW.dpbs
This URL does not display as a Summary Card when Tweeted: http://uat.legacy.com/news/legends/the-incredible-bill-bixby/1149/
Why would the Summary Card work in some instances and not others?