In previous versions of the sonos app you could select multiple speaker groups as outputs allowing you to quickly stream to multiple groups.

I dont know when it changed but groups can no longer be multi selected. Selecting a new group removes the previous selected speakers and replaces with just the new group.

For example, if you have Group A, B and C you used to be able to quickly output to groups A and B by selecting both groups. With new behaviour you can only ever select group A or B. The workaround is to create another new group D containing A+B, but this very quickly becomes unmanagable if you have more than 3-4 core groups.

This functionity change has significantly reduced the usability of the groups in my opinion. Did it get removed on purpose or can i re-enable the behaviour somehow?