I just wanted to listen to radio from the BS9000 in my living room with BS3 and in the bathroom with BeoPassive to Mac mini which is connected to the BS3 in the living room. But this doesn't work. I can listen to the Mac mini in the living room and radio in the bathroom but not vice versa. If I select Mac mini in the bathroom, the living room changes from radio to mac mini.

My BS3 was updated to 8.12 three days ago... and my feeling tells me that this worked before

Can`t have worked before. When you are listening to RADIO in the mainroom, Masterlink is occupied by the RADIO signal. So no way to get a different signal onto the Masterlink. When you are listening to the Mac in the mainroom, Masterlink is free to send audio to linkrooms, because the Mac is connected via analog stereo or spdif to your BS3. But you can listen to a video source  in video linkrooms, because in this case audio is distributed via antenna cable to (video) linkrooms. Hope this helps.

Stefan

Thanks Stefan! This explains everything! Really strange I didn't tried it before...