Roon Integration

Hello there.
I have tried the Roon integration the other day and i am missing a basic feature.
Or am i just using it the wrong way?
I have a group of speakers which appear like this in Roon software:

on the remote two display it looks like this:

My problem is that i have no idea how i can adjust the volume of just one speaker nor can i adjust the volume of all speakers together. If i press volume +/- it just adjusts the Volume of the first speaker in that group.
Has anybody got an idea what i am doing wrong or ist that still work in progress on that integration?

Thanks and cheers