Arc and Beam volumes are linked

I have three sound bars in three separate rooms.  Arc (family room), Beam (attic), Beam (master bedroom).

The Arc and the Beam in the attic room have a linked volume, but they are not grouped and are not playing the same media. For example:  If I am listening to music on one, and someone is watching TV on the other, the volumes raise and lower together as each user changes the volumes for their media in their room.

This does not happen with the other Beam in the bedroom. 

Any ideas what's up, or how to fix this issue?  I have tried grouping with other rooms, ungrouping, etc.

Thanks!