Update to Clock app breaks it

Short answer​

• There isn’t an official Microsoft notice (as of Sep 6, 2025) about a widespread Clock bug that auto-reschedules missed alarms. Please report it via Feedback Hub so it gets triaged quickly. Press Win+F right after the miss, describe “Clock alarm rescheduled for tomorrow,” and attach a recording/screenshot. (support.microsoft.com)
• Rolling back a Microsoft Store app to a previous version isn’t supported for end users; the Store only offers the current build. (learn.microsoft.com, answers.microsoft.com)

Quick fixes and checks​

• Settings > System > Notifications: On, and Clock is allowed (banners + sound). Turn off Do not disturb or add Clock to Priority. Also ensure the PC is awake at the alarm time; alarms/toasts don’t show if the device is sleeping. (support.microsoft.com)

• Settings > Apps > Installed apps > Clock > Advanced options > Repair. If no change, Reset. (makeuseof.com, thewindowsclub.com)

• Open PowerShell (Admin) and run:
  Get-AppxPackage Microsoft.WindowsAlarms | Remove-AppxPackage
  Then reinstall “Clock” from Microsoft Store (Library > Get updates). (answers.microsoft.com)

• Set a one‑time alarm 2–3 minutes ahead (ensure it isn’t set to repeat daily). Keep the device awake and volume up to confirm it fires. If it still misses and then shows “tomorrow,” capture that via Win+F and submit to Feedback Hub. (support.microsoft.com)

Workarounds (while Microsoft fixes it)​

• Use Outlook/Calendar or Microsoft To Do reminders for time‑sensitive meds/meetings, since they generate standard notifications independent of the Clock app. And consider a dedicated hardware timer/phone alarm as a temporary safeguard.

• Windows version (Settings > System > About), Clock app version (Settings > Apps > Clock > Advanced options), and whether the alarm was set to repeat. Also, was the PC asleep at the time? This will help pinpoint whether it’s a notifications/sleep issue or an app regression.