I did find this online, but not sure if it’s related… it just left me wondering if, because of its software vulnerabilities, the device was perhaps not being supported ..?

https://community.wd.com/t/important-announcement-about-your-wd-my-book-live-product-wdc-21008/268147

I would just call Sonos Support and see if they can assist. 

Which controller are you using? On speculation, force close the controller and restart. Another tactic is to uninstall the controller and fetch a fresh copy from online. Nothing critical is stored in the controllers, but if they get their nickers tied in a knot, interactions can be strange.

Tried this didn’t  work mate.

Spoke to WD about this. My server is not on the internet. It’s only set up on my local network. They told me to do a factory reset which I carried out. Re added my music but it still won’t index.

Have you tried each of the different versions of SMB? - perhaps start with the share set to use SMBv1, then v2 and then v3 and see if that gives access.

Edit: also use the NAS admin login credentials in the Sonos Library setup too (if that user account is not included already). 

How are you viewing and playing these tracks? Are you able to play these tracks using a SONOS controller or are you using a 3rd party program, such as AppleMusic? The SONOS Library Index and Playlists are stored in the players and are not visible to 3rd party applications.

When you attempt to index the library are any error messages posted? If you use a desktop controller, go to Help → Error Log… . Something might be posted here.

Ken what is an SMB? 

I’m using the S2 app on an iPad which was updated last month.

The message reads

MyBookLive/Public Music is no longer available.

SMB is a protocol used to access files on the NAS. If you are using a SONOS S2 system this doesn’t matter to you. SMBv1 is a very old protocol that has some security vulnerabilities and use of SMBv1 is discouraged. SONOS S1 only supports SMBv1. S2 will support the newer, more secure versions of SMB, along with SMBv1.

Recently, NAS manufacturers are taking a hard line and disable SMBv1 as the default and some manufacturers make the user jump through hoops to enable SMBv1. Computer operating systems are beginning to take the same approach.

The SONOS controller would display an error message if you are having an SMB issue.

Server Message Block  

It’s the client-server protocol that is used to (securely and effectively) share the NAS library, where clients request a file, and the server provides it to the client. just a mechanism to share the files between the NAS and the Sonos Speakers in this instance.

With each upgrades of its versions, the services are much more enhanced, effective and secure to store, transfer files etc.

I think you will likely find settings on your NAS configuration pages to change the SMB version, either for each shared folder, or globally.

edit: @buzz beat me to it.

Ah, you were typing as I was typing and I’m slow. If I auditioned for the typing pool, they’d toss me in the first few minutes.

I’m using an iPad, PC and Android and I suspect that Ken is mostly using an iPad. I mostly update the music library using the PC. 

I don’t recognize the error message. I’ll note that I am generally reluctant to have blank characters in share and file names. SONOS does not write anything in the music library files. I wonder if an update to the NAS has resulted in a subtle change in the share or folder name. Check your names with a fresh eye. Other than an iPad that I need for work, I’m not an Apple person. Based on comments that I read here’n there it seems that AppleMusic will move things and forget to tell anyone. You may be a victim of this sort of activity.

I am experiencing the same thing, although mine failed to index after an update about 3 months ago.

I have a My Book Live and use a Roam and the S2 app on both Android and PC.

There is no way to check/modify SMB in the interface of the My Book Live but as mentioned, that’s not a problem for S2 products. 

I have found that creating a new folder with some music and re-indexing to that works but also there appears to be a size issue. I’ve had a 3gb file index fine but over 15gb it seems to struggle with. This is a long way off the 65,000 song limit of a Sonos library though so it doesn’t make a lot of sense. 

What did Sonos say when you sent in a diagnostic and called them?