AFNetworking POST to webservice in Background via Location Updates

Question

I'm trying to POST to a webservice when my app is in the background. I've already enabled "Background modes Location updates" and checked for always on location.

When my app is in the foreground it posts fine. However as soon as I enter background and walk around it won't post. Is there an additional setting I need to actually have the location POST while in background?

- (void)locationManager:(CLLocationManager *)manager didUpdateLocations:(NSArray *)locations
{
    CLLocation *mostRecentLocation = locations.lastObject;
    NSLog(@"Current location: %@ %@", @(mostRecentLocation.coordinate.latitude), @(mostRecentLocation.coordinate.longitude));

    // my AFnetwork POST here

}