My alarm clock (Cesium) isn't providing sound.

I am a Mac user, so I understand that Bob's alarm can't be installed (I assume b/c it uses an exec file). Am trying Cesium (used to use Big Clock, which I loved).

Problem is that Cesium alarm goes off but with no sound. Seems like the first time I tried Big Clock it made a brief sound and then never again. Anyone know how I can get the alarm sound to come back on? (I assume Cesium works with sound?)