Symfonisk (Sonos) Speaker. Not all Stereo Pairs found -> Not playing

I have a couple of Sonos speakers (Ikea symfonisk). All are paired to stereo pairs. One pair is in my living room , another in my bathroom. The pair in the living room is discovered as stereo pair but the pair in my bathroom not. Can someone explain this behaviour?
I can also add the pair in my living room, add a radio channel to a thing and it is playing. The pair from my bathroom is discovered as two speakers. No matter what speaker I add from the bathroom I can not play anything on them. I also deleted the openhab cache but it still does not work.
can someone help me out? (I don’t want to configure it by config files)