HomePod Alarm with playlist not working - alarm sound instead

Since a few days now my HomePods mini are not able to work properly when I try to set up an Alarm with a specific sound from my library or a playlist. Instead the alarm sound is ringing. I tried several things to remedy to this issue. I set up a unique song, a playlist, an ambiance sound. I reinitialised the HomePods, decoupled them, recoupled them. I deleted and recreated the alarms several times. I can't find the solution. Sometimes it works in the evening when I try but then every morning the same issue comes back and the sound of alarm rings instead. Two changes have occured since this is happening: i updated the software on the homepods with the mast version and I create a stereo pair with a second homepod.