GMSMapView city labels disappearing

Question

Summary:

When using the GMSMapView object from the GoogleMaps framework (installed per pods from here: https://cocoapods.org/pods/GoogleMaps ) i have a strange issue when applying a custom mapstyle to the GMSMapView - the city and country labels are disappearing - this doesn't happen when i don't use any custom style for the map. (It doesn't matter which stlye attributes are set or not set it always happens for me)

Steps to reproduce:

I reproduced my issue in a Single View Application with only one ViewController where the map is constraint in Storyboard and linked to my ViewController.swift. The app looks like this:

AppDelegate:

class AppDelegate: UIResponder, UIApplicationDelegate {

    var window: UIWindow?

    let myGoogleMapsAPIKey: String = "[here goes my API-Key]"

    func application(_ application: UIApplication, didFinishLaunchingWithOptions launchOptions: [UIApplication.LaunchOptionsKey: Any]?) -> Bool {

        GMSServices.provideAPIKey(self.myGoogleMapsAPIKey)

        return true
    }

    func applicationWillResignActive(_ application: UIApplication) {}

    func applicationDidEnterBackground(_ application: UIApplication) {}

    func applicationWillEnterForeground(_ application: UIApplication) {}

    func applicationDidBecomeActive(_ application: UIApplication) {}

    func applicationWillTerminate(_ application: UIApplication) {}
}

ViewController.swift :

class ViewController: UIViewController {

    // mapView is linked from storyboard
    @IBOutlet weak var mapView: GMSMapView!

    override func viewDidLoad() {
        super.viewDidLoad()
        self.applyStyleToMap(self.mapView)
    }

    func applyStyleToMap(_ map: GMSMapView) {
        do {
            if let styleURL = Bundle.main.url(forResource: "mapStyle", withExtension: "json") {
                map.mapStyle = try GMSMapStyle(contentsOfFileURL: styleURL)
            } else {
                NSLog("Unable to find mapStyle.json")
            }
        } catch {
            NSLog("Map style failed to load")
        }
    }
}

mapStyle.json:

[
    {
        "featureType": "administrative.locality",
        "elementType": "all",
        "stylers": [
            {
                "visibility": "on"
            }
        ]
    }
]

Issue:

When zooming with a Pinch-Gesture into and out of the GMSMapView at specific zoom stages all labels are disappearing from the map with custom style. The Map then looks like this: (like mentioned this doesn't happen if no style gets applied)

Did anyone experience this is issue and can point me in the right direction? Am i missing a thing or is it a bug in the Google-Maps-iOS-SDK?

If you need further informations let me know i will provide everything you need.

Best Regards.