Xamarin.FormsでFunc<Task>を実行するとNotSupportedExceptionが発生する件

Xamarin＆Prismで以下のコードでNotSupportedExceptionが発生

/// <summary>
/// アクション実行
/// </summary>
/// <param name="action"></param>
/// <param name="errorAction"></param>
public static async Task ExecuteAsync(IPageDialogService pageDialogService,
Func<Task> action,
Func<Task> successAction,
Func<Exception, Task> errorAction)
{
    try
    {
        await action();

        if (successAction != null)
        {
            await successAction();
        }
    }
    catch (BusinessApplicationException ex1) when (ex1 is ApiTimeoutException)
    {
        await ShowDialogTimeoutAsync(pageDialogService);

        await errorAction?.Invoke(ex1);
    }
    catch (BusinessSystemException ex2)
    {
        // TODO:継続不可能例外
        throw;
    }
    catch (Exception ex3)
    {
        throw;
    }
}

Visual Studio 2017 15.3.2で解消してることを確認

ちなみにAndroid限定らしい