Hi there!
We’ve been using summary card for a long time with no problem, but we think that summary_large_image will do better for our tweets.
We’ve configured all needed meta-tags and finally spotted that when we use CDN URL for twitter:image, image proxy server returns an error (watching network traffic on Chrome Dev Tools, this should be visible on card test page)
On CDN we have whitelisted
*.twimg.com
*.tweeter.com
and in our robots.txt we’ve added
User-agent: Twitterbot
Disallow:
What else could be happening? We use max-cdn.
Example Card page:
http://asturias.eldesmarque.com/sporting/noticias/8132-muniz-fernandez-el-balon-le-da-en-el-hombro-y-puede-llegar-a-darle-en-el-brazo
Example image URL:
http://eldesmarqueasturias.eldesmarqueporta.netdna-cdn.com/images/2014_15/SPORTING/Arbitros/1389098406_723631_1389104047_doscolumnas_normal.jpg
We do not use SSL on our website so I think reported SNI problem is not the case.
Hope we can get some light into this. Thanks!