RadioPublic Player Onebox

I’m trying to embed podcast players from RadioPublic. Posting a link only gets me a standard onebox:


But RadioPublic claim that they use oEmbed. I have inline onebox on all domains enabled and I have also whitelisted https://radiopublic.com for iframes.
Using embed codes from RadioPublic works fine and embeds players correctly, but it would be much easier for users to just use the URLs.
Is this a Discourse issue at all or should I approach RadioPublic about this?

I stumbled upon this discussion


and now I’m wondering if the problem with the RadioPublic player is similar? Can you do the same thing for RadioPublic, @nbianca ?
Edit: It works, but not in the post preview. Only when I publish the post, the player appears.
Edit 2: After further research, it turns out that Stitcher links also don’t work, even though they do on iframely.

Soundcloud links also don’t show the player in post preview.