QML custom QDeclarativeItem based elements are not showing QString properties in Qt Creator's Design view, also not showing in editor's code hinting.

If you design custom components in C++ that are based on QDeclarativeItem for the consumption of QML elements, the QML editor does not show fields/Q_Properties with types such as QString. The Design section of Qt Creator does also no show QString fields/Q_Properties. I had qreal fields/Q_Properties which worked and was surprised that despite the connection to QString fields are established and works, the editor and Design section don't recognise them.