Hello @Cleve ,
yes, its an mp3 file (I also tested with other assets such as png), and the upload location is obviously correct (when I C&P the upload location to my browser’s URL field, append the slug and ‘.mp3’, it plays the file after loading).
I just realised that wordpress does not store field entries of the episode (number, title, subtitle, teaser, slug). When I save the episode, go to another section, say pages, and come back to the episode, its fields are empty (however, only reloading the page does not empty the fields’ content). Any experiences with that?