Location reminder not working on Android? How to fix late alerts
Short answer: allow location "All the time", exclude the app from battery optimization, and turn on Google Location Accuracy. Most "it never alarmed me" cases are one of these three.
1. Background location
Android only lets an app notice you arriving somewhere while it is closed if location is set to Allow all the time. "While using the app" is not enough for arrival alerts.
2. Battery optimization
Phone makers delay or kill background work to save battery. Open Settings → Apps → the app → Battery → Unrestricted (names vary by brand).
3. Location accuracy
Turn on Location Accuracy in Settings → Location. Without Wi-Fi scanning, geofences can trigger hundreds of metres late.
Choose a sensible radius
A 100 m radius can be missed when you pass quickly; 200–300 m is more reliable for walking.
How Herelet handles it
Arrival reminders are optional and off by default. Settings shows exactly which permission is missing and links to battery settings. If you don't allow background location, letters still open when you open the app near the place.
FAQ
Why does my GPS alarm work only when the app is open?
Location is probably set to "While using the app". Arrival alerts need "Allow all the time".
Does battery saver block location reminders?
Often, yes. Exclude the app from battery optimization.
What radius should I use?
200–300 m for walking; larger if you are driving.