On macos High Sierra 10.13 the QFileDialog stucks on the screen unresponsive after the file is choosen

I use a QFileDialog to let the user to choose a file, after the file is choosen with a double click or clicking on the open button the dialog stucks on the screen and is unresponsive. The only way to make the dialog to disappear is to minimize the main window and restore it.

The code I'm using is as follow:

QFileDialog dialog(this); 
dialog.setWindowTitle("Title"); 
dialog.setFileMode(QFileDialog::AnyFile); 
dialog.setNameFilter(filter); 
dialog.setViewMode(QFileDialog::Detail);
if (dialog.exec()) 
{ 
          QStringList files = dialog.selectedFiles();
          .......
}

I tried to use also the static form

QFileDialog::getOpenFileNames(this, "Title", filename, filter, &_lastFileFilter);

with the same result

I'm building my application with QTCreator 4.7.0 Based on Qt 5.11.1 (Clang 8.0 (Apple), 64 bit)

Thanks in advance