Compose Jetpack TwoPaneLayoutNav can find route for pane1 but not for pane2

Hi team, 

long time no see but here I'm with another problem which is properly caused by not understanding the API.

I use the version:

implementation("com.microsoft.device.dualscreen:twopanelayout:1.0.1-alpha06")

My code

Based on the tutorial, I tried to get my TwoPaneLayoutNav working.

class MainActivity : ComponentActivity() {
    override fun onCreate(savedInstanceState: Bundle?) {
        super.onCreate(savedInstanceState)
        setContent {
            val navController = rememberNavController()

            TwoPaneLayoutNav(
                navController = navController,
                singlePaneStartDestination = "regions",
                pane1StartDestination = "regions",
                pane2StartDestination = "regions"
            ) {
                composable("regions") {
                    RegionsScreen(
                        navigateToRegion = { id -> navController.navigate("regions/${id}")}
                    )
                }
                composable("regions/{id}") { backStackEntry ->
                    val id = backStackEntry.arguments?.getString("id")
                    RegionScreen(regionId = id ?: "A")
                }
            }
        }
    }
} 

The problem 

But as soon as I span the app across both screens, the app crashes with the following error:

java.lang.IllegalArgumentException: Invalid route regions, not present in list of routes []

I tried not just "regions" but "regions/a", too. Both does not work. If I introduce another path like "test" is also does not work. In single screen mode, everything works as expected.

Thanks for your help!