hello, normally when you are on your nas, with the search by artist / album you have the possibility of selecting with the letters on the right side.Cordially

Yes, and that works if accessing a library on my pc but does not show when accessing MyCloud, unfortunately.

For alpha-jump to show up on Sonos integrated services (eg Mycloud), that developer needs to implement it. Suggest you send them the link to these docs: https://developer.sonos.com/reference/sonos-music-api/getscrollindices/

Thanks. Are you saying to request or point out the problem to Sonos? I went on link and may have to set up account. Tony

No, the change needs to be implemented by Western Digital, who set up the plug in for MyCloud. Sonos provides the functionality already in the API, WD just needs to implement that part of it. 

Thanks again for your advice. I’ve re-looked and see a right hand scroll bar when accessing MyCloud Library on pc, but this is difficult to see & use on an Ipad. No letters can be seen on the right hand side in either case as you can see when accessing a Library from your computer.