Some times my alarm goes off completely normal, other times it goes off but only makes this 2 second "beep" chime only once. It's just one chime, no alarm sound, no nothing. The alarm GUI still apears on the screen. If it wasnt for the fact I'm almost awake at the time when it goes off, I would sleep entirely through the alarm.
It's the same alarm that will sometimes sound, sometimes not (I have it set to repeat M,W,F). It's a default alarm sound.
I know there's very little context to work with, but I have nothing else but this to provide you with.