Within Sonos app, go to Settings > Services & Voice > Amazon Music and reauthorise your account to see if that fixes your issue.

I have done that and I still get this message :(

Do you have a current Amazon Music Unlimited subscription or has it expired?

A subscription to Amazon Prime only will give access to a fraction of the songs compared to a subscription to Amazon Music Unlimited.

I don’t have the unlimited, I’m fine with the selection. 

Is that a way of compelling me to get unlimited?
That is a terrible thing to do.

Note that this is merely a pass through message, Sonos is merely displaying what they are getting from Amazon. Sonos is not making a choice here, Amazon is. 

Judging by the pop-up message, it suggests the music you are trying to play is not included within the free Amazon Prime music content available.

I've been listening to this Artist for a long time with no issues. Anything I choose is no longer available.

My Ikea Sono lamp is now just an expensive lamp.

I truly appreciate all of your extra help.

If you go to the actual Amazon Music app, are you able to play the songs there?

It’s possible the music you wish to play is no longer available under the free tier.

I installed the free app, and the music appears there. Something isn't right.

I'll uninstall and reinstall the Sono app.

That is unlikely to change anything. All Amazon configuration data is stored in the speakers, not the app.

Hi @PippiL 

Welcome to the Sonos Community!

I too have Amazon Prime and not Unlimited, and in my testing I was able to play the album shown in your screenshots. Unlike yourself, I am in the UK, but I don’t think Amazon makes that distinction when deciding you need to be on a different tier to play a particular track.

Interestingly, we were tracking an issue exactly like this back in 2019, and it was resolved by Amazon. In this case, however, we were able to reproduce the issue ourselves.

I recommend you contact Amazon support so they can assist.

I hope this helps.

Lol, thank you everybody. 

I discovered the mistake. My daughter and I share Amazon Prime, and her subscription has expired. It didn't appear until much later.