Podcasts App: Unplayed Episodes Show in Station Set For Unplayed Only

This is driving me mad. Stations on my phone are full of podcasts which are in the cloud and I have played at least once. The station is set for "unplayed only" but there are hundreds of episodes in the list with a cloud next to them which I have already listened to. If I go to the episodes in iTunes they show as played. I have had to spend hours (literally) swiping to delete hundreds of off-device episodes and my thumb feels like it will fall off.

Can anyone help me?

Please don't post a link to the standard Apple Podcast How-To. I've been there, and I've spent about an hour one the net trying to find answers.

Thanks in advance.