Downloaded/synced Podcasts still use mobile data

I’ve been playing Podcasts a lot over the last week or so, and I’m also experiencing the Podcasts stop playing then start at the beginning bug so the data consumed by Plex every time I play a Podcast has been huge - Every time a podcast loads or needs to be reloaded it chews down 50-300MB of mobile data!

These Podcasts are definitely synced and I have the prefer offline option switched on.