It might be that your Sonos and Mac aren’t using the same version of SMB, and you need to reset up your network share, but without more information, it’s really hard to be certain. I’ve been listening to iTunes (Apple Music) stuff since the change, originally on my Mac, now on my WD NAS. 

But I’d encourage you to submit a system diagnostic within 10 minutes of experiencing this problem, and call Sonos Support to discuss it. Don’t post the resulting diagnostic number here, they get sensitive about GDPR.

There may be information included in the diagnostic that will help Sonos pinpoint the issue and help you find a solution.

When you speak directly to the Support staff, they have tools at their disposal that will allow them to give you advice specific to your network and Sonos system.

Apple Music is not a problem. It is iTunes - music I have purchased. 

I will try your suggestion but I did that before and got nowhere. Thanks for your reply. 

Can you point us to where Sonos has said this is a problem and they are working on a solution? I do not remember Sonos having a problem with iTunes music specifically.

There is no ‘iTunes’ anymore, Apple rebranded that app as ‘Apple Music’. All of my local music was ripped by iTunes. Or purchased through. 

https://support.sonos.com/en-us/article/the-new-sonos-app-and-future-feature-updates
 

this talks about the problems with accessing and playing music purchased, that is in a local music library. 

It does. What did Sonos support tell you, when you called in?

That it is a known issue and they are working on a fix, and the fix would be announced. Nothing was announced and problem persists. Anyway, I will contact tech support again when I have time and hopefully the wait won’t be over an hour again. 

I’m not sure that it’s supposed to say that one cannot access local music, but more that some features were missing (adding folder to queue and fast scroll) which both have been restored in the last update. If you have problems accessing your library at all, I think that is a different issue.

I think it would be good, if you describe the issue you are seeing with your library, maybe someone here can help.