I've used Android for a decade. Always the same with the clock app, alarms, and timers. No issues until just this month: missed appointments, burnt and overcooked food, missed deadlines. The timer especially goes off but no sound, no screen wake up. It just starts counting down backwards in negative numbers, so when you do happen to open your phone, the alarm goes off and helpfully tells you just how overcooked your food is (23 minutes for this batch of granola, if you're wondering).