I have an MKMapView displaying realistic elevation. As soon as I call "mapView.addOverlays([polylines])" which then trigger: func mapView(_ mapView: MKMapView, rendererFor overlay: MKOverlay) -> MKOverlayRenderer { if let polyline = overlay as? MKPolyline { let view = MKPolylineRenderer(polyline: polyline) // ... return view } return MKOverlayRenderer(overlay: overlay) } The map instantly turn flat until I remove all the overlays.