Medium oneboxes are broken

Is there a reason why some domains/subdomains don’t appear as a onebox ?
I have added the domain in the whitelist - makes no difference:

Sample URL:

Probably it has no opengraph or oembed tags on the web page, or they are incorrect. Check the URL in Iframely URL Debugger - Open Graph, Twitter Cards, oEmbed

Yes, that seems to respond with the usual correct info and thumbnails etc ..

That does look correct, any ideas @techapj?

This issue is specific to Medium articles..

https://hackernoon.com/practical-functional-programming-6d7932abc58b

It seems like Onebox gem is unable to fetch HTML response for Medium articles. Added on my list to look into.

Created a PR for this:

https://github.com/discourse/discourse/pull/5457

PR is merged. Medium oneboxes works fine now: