Yep, similar for me. I can download the dialogue. However if I try to play it an online connection is used first. What‘s going exactly - I do not know.
However the data is available locally. If I disable the online connection (flight-mode) the dialogue immediately starts to play.
Thus I assume an artifact in the app-code referring to online-data if online-access is possible, ignoring that the data has already been downloaded.
I only do have EDGE-connection locally and the online request is a real pain as it lasts for ages.
Ah, and I‘m running iPhone and iPad with 11.2.1 of iOS.