yes we dont support sound in that particular tab as Android does not support it, you need to use the channel like I linked to and configure the channel in your device settings to use the desired sound.
check that your alarm stream has the volume set above 0, if its at 0 then yes you wont hear anything 
per the docs this can only be set once a channel has been created and cannot be changed once created. You either need to clear data in the app and set it up properly from the start if you wish to use alarm_stream or use a different channel that wont use alarm_stream. The only way to reset channel settings is to clear app data, removing a channel is a soft delete in android and it will retain all settings once enabled again.