VNRequest internalPerformInContext has not been implemented

I've been using the Vision object tracking code from the Apple example and others. This has been using swift and the programs work nicely.

I just ported the image recognizer to ObjectiveC with a few lines of code. But I get an error from the VNRequest handler:

error=Error Domain=com.apple.vis Code=8 "-[VNRequest internalPerformInContext:error:] has not been implemented"

My code is very simple taking a UIImage and looking for objects.

As I'm not processing video (yet) there wasn't a processor to initialize, but maybe there is something that needs to be initialized?

Any ideas?

Code Block 
-(void) processImageWithVision:(UIImage*) image
{
  CIImage* ciImage = image.CIImage;
  if (!ciImage) ciImage = [[CIImage alloc] initWithCGImage:image.CGImage];
  NSDictionary<VNImageOption,id>* dict = [[NSDictionary alloc] initWithObjectsAndKeys: @(0.8), @"confidenceThreshold", nil];
//Handler to process the image
 VNImageRequestHandler *imageRequestHandler = [[VNImageRequestHandler new] initWithCIImage:ciImage orientation:kCGImagePropertyOrientationUp options:dict];
// the handler that gets called
VNRequest *vnRequest = [[VNRequest new]initWithCompletionHandler:^(VNRequest * _Nonnull request, NSError * _Nullable error) 
{
  NSLog(@"vnRequest called %@, %@, error=%@",request, request.results, error);
}]; 
vnRequest.preferBackgroundProcessing = YES; //doesn't matter
//vnRequest to pass to the perform requests.
NSArray<VNRequest*>* vnRequests = [NSArray arrayWithObject:vnRequest];
//Schedules Vision requests to be performed.
[imageRequestHandler performRequests:vnRequests error:nil];
}