QFileDialog getOpenFilename getSaveFilename functions don't show captions and file filters on macOS

QFileDialog functions getOpenFilename and getSaveFilename are not showing any caption/title nor any file filtering options on macOS on their dialog windows, at least on Sierra and High Sierra (and possibly earlier).

If the option QFileDialog::DontUseNativeDialog is used, the dialogs do show titles and file filtering, but the dialogs look VERY different to - arguable far poorer than - the default macOS dialogs and their folder navigation method is very different to default macOS.