Work through this list. Most problems are one of these.
- Notification access is on for Notification Tracker (Android Settings).
- Notifications permission is allowed. Settings > General Settings > Notifications for alarms shows Allowed.
- Background activity is allowed so Android doesn't stop the app.
- The notification really matches the alarm: same app, sender and words. Check the notification in History.
- The alarm isn't in a Blacklisted app. Blacklisted apps can still ring alarms only if Process Blacklisted is on in Settings > Alarms.
- Alarm Volume and your phone volume aren't muted.
- For Do Not Disturb, both Ignore Do Not Disturb switches are on.
Still stuck?
Send us a bug report from Settings > About. Tell us the app and the phone model.