Downloaded Podcasts Automatically Removed

Hi,

This isn't the worst problem in the world but it's driving me nuts!

I subscribe to a number of podcasts on my iPhone XR. As far as I can see all my settings are configured to never remove downloaded podcasts (because sometimes it can take me a while to get to one).

And yet... periodically, downloaded podcasts vanish.

I can't tell if it's a matter of elapsed time, or upon the download of a more recent podcast, or what... but I'll go to the Downloaded section and notice that there are fewer podcasts there now than there were yesterday. I'll go to the Shows section and the podcast will appear there, un-downloaded, and I can download it again, no problem. It doesn't make a difference whether the podcast had been completely un-played or partially played.

Can anyone tell me why this happening - against my set preference - and what if anything I can do about it?

Thanks!

Stew