Driving activity confidence is low all time in iOS 11 - ios

Question

I've an application which detects user driving and do some process internally. After the iOS update from iOS-10 to iOS-11, the application stops working. Still the application works great in iOS 10, but fails in iOS 11.
After debugging I found that the CMMotionActivityManager had the issue. The confidence of the automotive activity is low (0) at most of the time even though the user is actually driving.
Since this I can't identify the complete driving behaviour of the user.
Here is the sample code I'm using.
if CMMotionActivityManager.isActivityAvailable() {
motion.startActivityUpdates(to: OperationQueue.current!, withHandler: {
activityData
in
self.handleActivityData(activityData!)
})
}
func handleActivityData(_ activityData: CMMotionActivity) {
let rawConfidence = activityData.confidence.rawValue
// Confidence = 2 -> high
// Confidence = 0 -> low
if rawConfidence > 0 {
if activityData.automotive {
drivingActivity = true
Log.info("Activity : Automotive")
} else {
drivingActivity = false
var text = "Empty"
if activityData.walking {
text = "Walking"
} else if activityData.running {
text = "Running"
} else if activityData.stationary {
text = "Stationary"
} else if activityData.cycling {
text = "Cycling"
} else if activityData.unknown {
text = "Unknown"
}
}
}
}
Do anyone face the same issue?
Any help is appreciated.