What do I do when iPhone shows a podcast episode "Temporarily Unavailable"?

This happens quite often.

The other day I started playing a "Science Friday" podcast while taking a walk with my iPhone and my Apple Watch. Instead of playing the new episode, it started playing an episode that I had already listened to. Checking the settings, of that episode, it had the option to Mark as Unplayed. I think it had an option to download. I fast forwarded through it, and it started playing the current episode. I finished my walk with it halfway played.

In my afternoon walk, I tried to resume it. My watch indicated it was playing, but no sound came out. I got out my phone and opened the app to see: Episode Unavailable This episode is temporarily unavailable from "Science Friday".

Options available are "Remove Download" and "Mark as Played". I returned home and saw that my iMac shows it partially played. I synchronized my phone. No help. I tried playing it the next couple of days, but the same problem persists.

In the past, I have gotten around this problem by playing it on my iMac. But that isn't an optimum solution.

What *should* I be doing?