Create Qt Quick Blank Project with default main.qml

import QtQuick 2.15
import QtQuick.Window 2.15

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

Go to design tab and Qt starts 3 processes with name Qml2Puppet (attachment 1)

And the qml file preview is empty(attachment 2). The content of the Window component does not change the behavior of the editor. If in main.qml I change "Window" component to an "Item" component preview works well, but expectacly window not create.