When I set an alarm (or set a timer) in Clocks in Ubuntu 20.04, the alarm clearly triggers as at the appropriate moment a notification appears at the top of the screen and I get a message in the Clocks application asking me to stop or snooze; however this is all silent - I get no audio alarm. I have another laptop still running 18.04 and the audio for these alarms works fine on that.
On my 20.04 machine, audio is functioning fine in other applications. I've checked that notifications are on. The Notifications settings in Settings for Clocks has notifications, sound alerts, notification popups and even lock screen notifications on. When in Settings I check Applications, GNOME Clocks has notifications on, too. In the sound panel, system sounds are on and they are turned up, and when I test the alert sound buttons I get an appropriate noise.
The version of Clocks is just the one that comes installed on the machine (ubuntu-focal-updates-universe), rather than a Snap or some such thing.
Could there be something I'm missing? Or might there be a bug in Clocks 3.36.0?