Q_GADGET's properties not recognized as members

I have defined a struct as a Q_GADGET and used it as a property of a QObject derived class. When I try to use it from QML, the editor says that my property does not have member, even though it has. The code works fine, only the editors (text and designer) fail to recognize the members.

This makes the designer unusable, as it will not display anything except an error dialog.

I've attached a simple code sample that shows the behavior and two screenshots - one shows the error in QtCreator and one shows the app running just fine, with correct behavior.