UIImagePicker only works with front camera on iPhone 6 plus

Using the following code:

- (void) viewDidAppear:(BOOL)animated {

    [super viewDidAppear:animated];

    if (!self.alreadyAppeared) {

        [self performSelector:@selector(showCamera) withObject:nil afterDelay:0.3];
    }

}

-(void)showCamera
{
    UIImagePickerController *picker = [[UIImagePickerController alloc] init];
    picker.sourceType = UIImagePickerControllerSourceTypeCamera;
    picker.showsCameraControls = YES;
    picker.cameraDevice = UIImagePickerControllerCameraDeviceFront;
    picker.delegate = self;

    [self presentViewController: picker animated:YES completion:NULL];
}

my app works perfectly. However if I change the

picker.cameraDevice = UIImagePickerControllerCameraDeviceFront;

to

picker.cameraDevice = UIImagePickerControllerCameraDeviceRear;

I lose the image. The following code is how I capture the image and set an imageview within my app. I use a Nav controller to return to the app:

- (void)imagePickerController:(UIImagePickerController *)picker didFinishPickingMediaWithInfo:(NSDictionary *)info {

    UIImage *chosenImage = info[UIImagePickerControllerOriginalImage];
    self.cf.imageView.image = chosenImage;

    NSLog(@"%@",chosenImage);
    [picker dismissViewControllerAnimated:YES completion:NULL];

    // pop back to previous controller
    NSArray *myControllers = self.nc.viewControllers;
    int previous = (int)myControllers.count - 2;
    UIViewController *previousController = [myControllers objectAtIndex:previous];

    [self.nc popToViewController:previousController animated:YES];

}

Again, this works just fine on my iPad and it works just fine using the front camera. Even when using the rear camera the chosen image (that I log) appears correct. Does anybody have any idea why the rear camera setting would have such an effect?

One other item: I get this very irritating message that has about 1,000 different explanations none of which get rid of the message:

Snapshotting a view that has not been rendered results in an empty snapshot. Ensure your view has been rendered at least once before snapshotting or snapshot after screen updates.