To dredge up an old thread
This happened to me again last week. Latest iOS whatever it is now.
It happens to me once a year or so. I never trust iOS as my primary alarm. I've been using Alexa as primary and iOS as my backup.
Alexa has failed twice also in the past few years, but seems slightly more reliable.
I never had alarms fail before my first iPhone. Even my 1990s cell phones ALWAYS worked. My Android phones ALWAYS worked.
Software uality control has been almost non-existent for the last ten years.
Even Boeing...