I've had this issue since last week and it was created either by a new version of 1.9a or a long power outage we had.
My main HM DVR was always first on the list when using the Multi-room feature of my 7200. However, now my son's DVR is first on the list - and i have to choose the main one each time I use it.
I noticed that the IP address of the HM DVR (main box) is higher (104) than the others. I've unplugged everything and reset the boxes, but the IPs don't change. I've renamed the main box thinking that 1.9a is now ordering the DVRs alphabetically, but that doesnt' work either.
I remember seeing posts about making certain DVRs the default, but I can't find the it now.
I'm wondering if what I'm referring to is a PRIMARY HUB and somehow it got reset to my son's DVR...Just a thought