UILongPressGestureRecognizer does not detect back-to-back long presses

Question

I have created a simple Swift application to test out the UILongPressGestureRecognizer. The app shows the world map (MKMapView) onto the screen where the user can long press on the map and I simply print out the number of times the user has long pressed on the map.

The problem is that when I long press on the map back-to-back, only every alternate long press is detected! So if I were to print out a counter variable which increases every time a long press is detected, I would expect the following:

1. I long press on map
2. Displays "Tapped 1 times"
3. I wait a couple of seconds and then long press on the map again
4. Displays "Tapped 2 times"
5. I wait a couple of seconds and then long press on the map again
6. Displays "Tapped 3 times"

Instead of the above correct functionality, I am getting the below:

1. I long press on map
2. Displays "Tapped 1 times"
3. I wait a couple of seconds and then long press on map again
4. Nothing happens!!!!
5. I wait a couple of seconds and then long press on map again
6. Displays "Tapped 2 times"

Here is my simple code:

// Global variable
var taps:Int = 0

@IBAction func longPress(_ sender: UILongPressGestureRecognizer) {

  if sender.state == .began {

    // Increment counter and print to output
    taps += 1
    print("Tapped \(taps) times")

  }

}

The above code is quite simple so I am not sure what is wrong?

Another interesting note is that if I add the below code after the print("Tapped \(taps) times") which calculates the position where the user long pressed and moves to that location via the mapView.setRegion() method, I get the correct functionality!!

let touchPositionOnScreen = sender.location(in: mapView)
let convertedLatitude = mapView.convert(touchPositionOnScreen, toCoordinateFrom: mapView!).latitude
let convertedLongitude = mapView.convert(touchPositionOnScreen, toCoordinateFrom: mapView!).longitude
let locationCenter = CLLocationCoordinate2DMake(convertedLatitude, convertedLongitude)
let currentSpan = mapView.region.span
let moveToRegion = MKCoordinateRegion(center: locationCenter, span: currentSpan)
mapView.setRegion(moveToRegion, animated: true)

Has anyone else observed this behavior? Please help.