Is it now 'safe' to upgrade the app?

If you use a NAS media library then I would say stay where you are.  There is still no playlist creation and editing capability in the Android and IOS apps and whilst the PC app does still have playlist functionality and works best of all the controllers there are indications that Sonos want to retire this asap.

My other biggest issue is that I have had extensive problems with the “Fragmented Compilation Albums” issue as documented in many other threads in this forum.

Also WAV files seem to be randomly affected by missing tracks from the Artist / Album view and I have spent hours converting albums to FLAC and re-tagging to overcome the fragmented album issue and the randomly missing tracks issue.   (despite these wav files having all the correct tags as shown by mp3tag and they all appear in the ‘folder’ view)

To give you an impression of what you might expect I have painstakingly checked the Artist / Album views against the folder view and found that 17% of albums in my library have 1 or more tracks missing from those views, mostly missing 1 or 2 tracks but occasionally half the album is missing yet all the tags are correct.  it is immensely frustrating. 

Its been 9 months of updates and still no sign of playlist management on the horizon.

Moderator edit: WAV files do not properly support ID3 tagging - they are not recommended for use with Sonos.

Thanks - I just hope that improvements in that area are made before I need to make any changes (e.g. move house, change router…...). I don’t have WAV files on my NAS, so that’s not an issue but playlist management would be more of an issue
Any comment from Sonos on any plans/timeframe? 

Did I not read the fragmented compilation album issue is caused by Sonos handling ID3 differently? And as such will not be mended/is not an issue according to Sonos?

No, it’s (still) a bug with the mobile app, and affects compilations and albums with guest artists on selected tracks. Standard ID3 tagging will have artist as “Artist; guest-artist” and album-artist as “Artist”. Sonos desktop app handles this perfectly. The mobile app (still broken with the new 16.7 release) simply “disappears” tracks with multiple artists, even though it should be a dumb client displaying what the “server” Sonos unit fetches. Known workarounds: 1. Use desktop app or third-party client, 2. Re-tag everything for Sonos (eg. the Qobuz approach of omitting the guest artist), 3. Create a playlist of any affected album.

I am assuming that if other services follow the Qobuz safe/minimalist approach to tagging, then Sonos have written this off as a “won’t fix” bug as it only affects those of us who buy/own music.

Corry has just posted an explanation on this subject at the end of the “fragmented compilation albums” thread that explains Sonos’s thinking and their recommendation to customers.

The latest app still lacks the ability to play or shuffle from the “Folders” view of a music library, and you cannot usefully pin folders to your Sonos home page. So if you use folders for high-level organization, the latest app is still a bust.