There are two possible causes for this. The first is that, because you can run HomeRoutines on more than one device, you are able to switch reminders off on one of them (so you don’t have every device in the house reminding you it’s time to pack the lunchboxes)

How to check this:
1) Tap “Help and Settings” at the bottom of the home screen
2) Tap “Settings”
3) Ensure that the switch for Reminders is set to On.

The second possible reason may be that your local notifications for the app are switched off.

How to fix this:
1) Open your device’s Settings app
2) Tap “Notifications”.
3) Scroll down, and you’ll probably see HomeRoutines in the “Not in Notification Center” section.
4)Tap that line, then turn on “Notification Center”, set the Alert Style to “Alerts”, turn on “Sounds” and turn on “View in Lock Screen”.