winrt消息对话框未显示

我正在尝试在桌面Windows应用程序中的C (WinRT(中显示一个消息对话框，定位10 x64。以下代码执行，但未显示对话框。ShowAsync的返回代码很好

int APIENTRY wWinMain(_In_ HINSTANCE    hInstance,
                         _In_opt_ HINSTANCE hPrevInstance,
                         _In_ LPWSTR        lpCmdLine,
                         _In_ int           nCmdShow)
    {
      Microsoft::WRL::Wrappers::RoInitializeWrapper init(RO_INIT_SINGLETHREADED);
        Microsoft::WRL::ComPtr<ABI::Windows::UI::Popups::IMessageDialogFactory> messageDialogFactory;
        Microsoft::WRL::Wrappers::HStringReference messageDialogFactoryId(RuntimeClass_Windows_UI_Popups_MessageDialog);
        Windows::Foundation::GetActivationFactory(messageDialogFactoryId.Get(), messageDialogFactory.GetAddressOf());
        Microsoft::WRL::ComPtr<ABI::Windows::UI::Popups::IMessageDialog> messageDialog;
        Microsoft::WRL::ComPtr<ABI::Windows::Foundation::Collections::IVector<ABI::Windows::UI::Popups::IUICommand*>> uiCommands;
        messageDialogFactory->CreateWithTitle(Microsoft::WRL::Wrappers::HStringReference(L"XXX").Get(), Microsoft::WRL::Wrappers::HStringReference(L"YYY").Get(), messageDialog.GetAddressOf());
        messageDialog->get_Commands(uiCommands.GetAddressOf());
        Microsoft::WRL::ComPtr<ABI::Windows::UI::Popups::IUICommandFactory> uiCommandFactory;
        Microsoft::WRL::Wrappers::HStringReference commandFactoryId(RuntimeClass_Windows_UI_Popups_UICommand);
        Windows::Foundation::GetActivationFactory(commandFactoryId.Get(), uiCommandFactory.GetAddressOf());
        w::ComPtr<pu::IUICommand> button;
        uiCommandFactory->CreateWithHandler(Microsoft::WRL::Wrappers::HStringReference(L"ZZZ").Get(), new ButtonHandler(), button.GetAddressOf());
        uiCommands->Append(button.Get());
        Microsoft::WRL::ComPtr<ABI::Windows::Foundation::IAsyncOperation<ABI::Windows::UI::Popups::IUICommand*>> showOperation;
        HRESULT hr = messageDialog->ShowAsync(showOperation.GetAddressOf());
        MSG msg;
        while( ::GetMessage(&msg, 0, 0, 0) > 0 )
        {
            ::TranslateMessage(&msg);
            ::DispatchMessage(&msg);
        }

      return 0;
    }