[Bug]: With `disableMotionActivityUpdates: true` and `useSignificantChangesOnly: true`, background location does not seem to work properly anymore

[justChris]

Required Reading

• Confirmed

Plugin Version

4.16.12

Flutter Doctor

Doctor summary (to see all details, run flutter doctor -v):
[✓] Flutter (Channel stable, 3.32.7, on macOS 15.5 24F74 darwin-arm64, locale en-US)
[✓] Android toolchain - develop for Android devices (Android SDK version 35.0.0)
[✓] Xcode - develop for iOS and macOS (Xcode 16.4)
[✓] Chrome - develop for the web
[✓] Android Studio (version 2024.3)
[✓] VS Code (version 1.102.1)
[✓] Connected device (3 available)
[✓] Network resources

• No issues found!

Mobile operating-system(s)

• iOS
• Android

Device Manufacturer(s) and Model(s)

iphone 15 pro

Device operating-systems(s)

iOS 18.5

What happened?

With disableMotionActivityUpdates: true and useSignificantChangesOnly: true, background location does not seem to work properly anymore.

App is terminated over night. In the morning I go to work (Thats a few kilometers). I do not get any location updates.
When I then start the app, I get location updates. When I terminate the app again, background location updates keep emitting when I move around.

Can you imagine why that is?

Plugin Code and/or Config

_state = await bg.BackgroundGeolocation.ready(
      bg.Config(
        reset: true,
        notification: bg.Notification(smallIcon: '@drawable/ic_stat_name', largeIcon: '@mipmap/ic_launcher_foreground', channelName: 'Background Location'),
        locationAuthorizationRequest: 'Always',
        backgroundPermissionRationale: bg.PermissionRationale(
          title: 'Allow App to access your location in the background?',
          message: 'Your background location data will never leave your device!',
          positiveAction: 'Allow',
          negativeAction: 'Cancel',
        ),
        desiredAccuracy: bg.Config.DESIRED_ACCURACY_HIGH,
        distanceFilter: 50.0,
        stopOnTerminate: false,
        startOnBoot: true,
        enableHeadless: true,
        disableLocationAuthorizationAlert: true,
        disableMotionActivityUpdates: true,
        useSignificantChangesOnly: true,
        persistMode: 0,
      ),
    );

Relevant log output

[justChris]

@christocracy are you working on this?

[justChris]

In #1536 I refactored this original issue, because it only happens on iOS.

With useSignificantChangesOnly: true, no location updates will be emitted while app is terminated. When app is started or in background it works. Either with disableMotionActivityUpdates: true or with disableMotionActivityUpdates: false, as soon as I terminate the app, it stops working.

On android on the other hand, it works flawlessly, either with disableMotionActivityUpdates: true or with disableMotionActivityUpdates: false. The headless task keeps emitting location updates when app is terminated.