Vision yawAngle sensitivity

I'm using Vision to detect yaw angle of the face.

Code is similar to below:

try? self.faceDetectionRequest.perform([self.faceDetection], on: image)

guard let results = self.faceDetection.results as? [VNFaceObservation], results.count == 1 else {

completion(nil)

return

}

let yaw = results[0].yaw

if let yaw = yaw {

print("yaw = \(yaw)")

}

The problem is I can only get new value for each 45 degree changes. (I can't get the correct yawAngle value when the user rotated his head 30 degrees. YawAngle was only updated once its changed for 0,45 and 90 degrees)

Is it intended behaviour or bug which will be fixed in the future ?

I also want to know is there any other option to have more sensitive values.

Thanks.