I cannot add to the Playlist anymore / the 'add to playlist' button has disappeared
Since v3.9 the app uses a new default playlist mode called 'Continuous Playback'.
This mode allows the app to manage the playlist automatically: press play on an episode and the app will automatically queue unread episodes of the same podcast.
Only the default Audio/video playlists allows you to add contnet to the playlist manually.
You can disable the 'Continuous Playback' mode in the app Settings/Playlist screen