How to use UWP FolderPicker in a WPF c# desktop app

I have a WPF desktop app and I want to use the UWP FolderPicker API to pick a directory. My app uses the UWP packaging project so it is built and ran as an appx. I've added in the Windows and WindowsBase references and my project builds and runs. However I get a runtime error when trying to use the folder picker. My code is as follows:

    private async void OnGetDirectory(object parameter)
    {

        var folderPicker = new Windows.Storage.Pickers.FolderPicker();
        folderPicker.SuggestedStartLocation = Windows.Storage.Pickers.PickerLocationId.Desktop;
        folderPicker.FileTypeFilter.Add("*");

        Windows.Storage.StorageFolder folder = await folderPicker.PickSingleFolderAsync();
        if (folder != null)
        {
            // Application now has read/write access to all contents in the picked folder
            // (including other sub-folder contents)
            Windows.Storage.AccessCache.StorageApplicationPermissions.
            FutureAccessList.AddOrReplace("PickedFolderToken", folder);
        }
        else
        {
        }
    }

The error I get is on the line System.Exception: await folderPicker.PickSingleFolderAsync(); and the error 'Invalid window handle. (Exception from HRESULT: 0x80070578)'

What am I missing or is it even possible to use the FolderPicker from a WPF app?

Instead of UWP FolderPicker you can just use a normal Windows Forms folder dialog - FolderBrowserDialog in System.Windows.Forms namespace (see this question for an example).

If you want to work with StorageFolder, you can call StorageFolder.GetFolderFromPathAsync method or you can use the classic folder APIs like System.IO.Directory or System.IO.DirectoryInfo.