SKNavigationDelegate current advice returning nothing

Question

I am using the navigation in SKMaps and my class is using the SKNavigationDelegate which provides the following method:

func routingService(routingService: SKRoutingService!, didChangeCurrentAdvice currentAdvice: SKRouteAdvice!, isLastAdvice: Bool)

The documentation says that currentAdvice should provide the current advice string. I'm using

currentAdvice.adviceInstruction

But that is returning an empty string... Am I missing something?

Also in this delegate method I'm trying to use the advice and put it on the screen as a label, however I can't seem to get the label text to appear... I set a breakpoint so I know the method is being called but it just outputs an empty label. Any ideas?

Edit: added settings:

In my SKRouteSettings I have

let route = SKRouteSettings()
route.startCoordinate = SKPositionerService.sharedInstance().currentCoordinate
route.destinationCoordinate = destinationCoordinate
route.shouldBeRendered = true // If false, the route will not be rendered.
route.routeMode = SKRouteMode.Pedestrian
route.maximumReturnedRoutes = 1
route.requestAdvices = true

And SKNavigationSettings

let navSettings = SKNavigationSettings()
navSettings.navigationType = SKNavigationType.Simulation
navSettings.distanceFormat = SKDistanceFormat.MilesFeet
SKRoutingService.sharedInstance().mapView.settings.displayMode = SKMapDisplayMode.Mode3D
SKRoutingService.sharedInstance().startNavigationWithSettings(navSettings)