I’m not a Podcast user but I assumed they were tiered just like some music streaming services. You have to pay for commercial free Podcasts. 

What service are you accessing the streams from?

TuneIn is the service causing the most problems. I'm not looking for ad free programming necessarily I just don't want ad-only programming which is what I'm getting now. There is no content aside from an endless stream of ads. And, yes, I'm using what is supposed to be the new Sonos TuneIn app.

It has been reported by another user in later posts on the following thread:

I’ve also tried to play a podcast from TuneIn and the integration is currently broken.

You would be best to contact Sonos Support so they have cases to review.

Yeah that comment that “You have to pay for commercial free Podcasts.” is pretty funny and wildly off the mark
 

I used to use Pocketcasts on Sonos for podcasts. You might want to check it out, it’s still available. 
 

Since the app disaster last year I’ve switched to using the Apple Podcast App. It provides a much better experience than the Sonos app IME but YMMV (need to be an iPhone/ipad user). 

I’m having this too .  Podcast content is on TuneIn and I can play it on my PC no issues.  When I try to play on Sonos I get an endless loop of “Welcome to Tunein”, followed by an advert, then back to “Welcome to Tunein”.  All other services that I use work fine, so frustrating! 

Tried re-authorizing;  deleting Tunein+ re-authorise; reset my router but nothing :-(

Running Android and PC platforms, please fix:-).  Peter