If you are not receiving reminder notifications, please check the following settings in your phone's Settings app.
- Open your phone's Settings app.
- Tap "Notifications" → "App notifications".
- Under "Most recent", find apps that recently sent you notifications.
- To find more apps, tap "All apps" in the dropdown menu.
- Tap the app.
- Turn the app's notifications on or off.
- You can turn off all notifications for a listed app.
- To choose specific categories of notifications, tap the app's name.
* If you don't see "Recently sent", you're using an older Android version. In that case, tap "App notifications" and tap the app. You can turn notifications, notification dots, and notification categories on or off. If an app has categories, tap a category for more options.
Also make sure "Reminder" in the app's settings menu is turned on. In addition, Android has a battery-saving feature (Doze mode) that often delays notifications while the device is asleep. Please check this as well.