Диалог сообщений Winrt не отображается

Я пытаюсь отобразить диалог сообщений в C ++ (winrt) из настольного приложения для Windows, ориентированного на Win 10 x64. Следующий код выполняется, но диалоговое окно не отображается. Код возврата из ShowAsync хорош

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;
}