Ungrouping works, grouping does not

[hexadecagram]

It seems that a recent Sonos update made it so.

[lfaraone]

Works for me; I was able to create a zone by just dragging and dropping.

• Controller: version 6.3.2 (build 321131051)
• PLAY:5 version 6.3 (build 321130162a)
• PLAYBAR: version 6.3 (build 321130071)

[jishi]

Works on my machine, although it can be improved for systems with many players.