Whenever I have to wake for something that I absolutely can’t miss, I set 2-3 extra reminders 5 minutes apart precisely because of this “silent alarm” bug. It’s only happened to me a couple of times but twice was enough to completely destroy my trust in the alarm. The first time I thought I just did something in my sleep to cause it, but the UI shows it as if the alarm worked. I’m lucky to have the privilege that if I oversleep an hour or so it’s no big deal, otherwise ye olde tabletop alarm clock would be back.