Qt Creator does not work with QML debugger as expected

import QtQuick
import QtQuick.Controls

Window {
    width: 640
    height: 480
    visible: true
    title: qsTr("Hello World")    

function toggleRectangle() {
        let currentVisibility = rect.visible
        rect.visible = !currentVisibility
    }    

Rectangle {
        id: rect
        width: parent.width / 2
        height: parent.height / 2
        anchors.centerIn: parent
        color: "lightblue"
    }    

Button {
        anchors.bottom: parent.bottom
        anchors.horizontalCenter: parent.horizontalCenter
        text: "Click"
        onClicked: toggleRectangle()
    }
}