Thanks for the response, Marco (^_^)
That is a shame. If any creator or service should be considered as a partner I think Overcast should. So when Twitter said they “plan to make it available to more partners and creators,” I guess that was another empty promise made to developers.
I could have sworn SoundCloud sounds were able to play in the background, but when I tried to play a podcast on the Twitter Android app it just stopped when I put it in the background, and all the normal player cards (including Overcast, unfortunately) just open the players in Chrome. On iOS, tapping the play button doesn’t do anything at all. I think you’ve done everything right according to the documentation, but this makes me think cards have taken a back seat in favor of more ads or Periscope or whatever.
I’m curious - do you know if Overcast’s cards ever worked on mobile?