Use Cellular Data to playback podcast

I download all my podcasts over wi-fi at home. When I try and play them back I get a message asking me "Use Cellular Data - Would you like to temporarily turn on Cellular Data in order to play back this streaming episode?" The only option to play the podcast is "Turn On", regardless of whether there is a wi-fi connection or not. In Settings/Podcasts I've set Use Cellular Data to OFF.

Why if the podcast is already donwloaded would cellular data be required to playback a streaming episode - there's no need to stream if its already downloaded.

This has never been a problem before but has been the case ever since I used ceelular to download a podcast on the bus as a once-off. Podcasts Version is 1.2.1 (331)