In Qt 6.9.1 and MacOSX15.5 do not select "Run in terminal" since this will block the QML debugger. The C++ debugging will work. Select instead "Run as root user" option in the Run configuration. It is annoying to always type the root password when the application starts, but at least it runs.

This is still not fixed. However, there is a workaround. Run application in terminal (QtCreator :: Projects->Run->Run in terminal). I have tested it with QtCreator 16.0.1 and Qt 6.9.0 on MacOSX 15.3.2.