It's just one of many missing features in the half-baked app.  It's scheduled to be back in a coming release.  Until then you can use the PC or Mac controller to manage your local library.

Thanks, I have spent a huge amount of time and £££ getting my library sorted only for Sonos to drop the ball, with an un asked for update and a shoddy app. They have lost a supporter with me.

I don't have a Mac or PC controller, just an android phone and an iPad, which have been fine in the past. Thanks a bunch Sonos