I’m encountering the same issue wherein the alarm does not work.
The alarm doesn’t seem to work even if I try setting it several times! Tried rebooting etc and still the same on an Era 300. Any workaround?

sonos 

is working on bring the alarm setting back they are fix it and will put in a new app update when ready

run the alarm though the app on the computer and you will be ok till the app is re done with the up date

I’ve updated the app but still alarms are not saving properly.