Agreed, my original posts for this issue in July are now locked.
FYI: I simply did the Firmware Update and it resolved the issue for me.
I didn’t have to remove/add my library.
Ross.

I have updated firmware as well but this is not fixed in my case. Have removed the library and re-added on both Windows app and Android app, rebooted all devices in between. No change in the compilation albums showing up multiple copies.

 For compilations to show properly the Album Artist tag should be the same for all tracks; Something like Various Artists.  The Artist tag should be the performer for each track.  Then when you look at the Albums category there will be one album with the tracks in the proper order.

 When I updated to firmware 16.4.2 (build 81.1-58074) I did not even have to index the library; it automatically changed.

Which means I need to add the tag for each of my compilations. Just did this for one album and I do need to rescan to update but that does it.

This is not how other music renderers handle compilations but I'm willing to update the 75 albums I have just to fix this.

 Glad that worked.  One thing I learned years ago was to try to tag in a manner that works for all server, controller software.  Learned some “pain-in-the-butt” lessons along the way.

There’s a setting that’s still missing in the new app, (I know, it must be your network) which tells the Sonos indexer on the speakers whether to use the iTunes compilations tag, Album artist, or to not group them.  

It’s possible you have the wrong one in force, I don’t know what the default is if it has never been set. I suspect a few people have factory reset since May and this might have changed as a result. You can get to it still in the desktop apps while they’re still here… 

I imagine at some point these options might make it through to the new app….