Mixed C++/QML debugging is broken on Android

There are several issues with it:
1. When starting a debugging session the "start" button in the debugger toolbar goes into the "continue" state (|>). It should rather enter the "pause" state (||),
2. When pressing the button, the application stops and QtCreator complains:

Application process could not be stopped:
Remote connection closed

3. The QML object structure is not shown in the locals and expressions view. The l&e view seems to remain in the "C++" state.

It seems we don't connect to the QML debug server, either because that is not started or because the connection fails.