Invalid alias target location unless I bind it

    property alias monitorLabelText: monitorForm.monitorLabel.text
    header: MonitorForm {
        id: monitorForm
    }

    property alias monitorLabelText: monitorForm.monitorLabel.text

    header: MonitorForm {
        id: monitorForm
        monitorLabel.text: '' // added
    }

    property alias monitorLabelText: monitorForm.monitorLabelText // <-

    header: MonitorForm {
        id: monitorForm
    }

from PySide6.QtGui import QGuiApplication
from PySide6.QtQml import QQmlApplicationEngine

app = QGuiApplication()
engine = QQmlApplicationEngine()
engine.load('test.qml')
app.exec()

import QtQuick.Controls

ApplicationWindow {
    visible: true
    property alias monitorLabelText: monitorForm.monitorLabel.text
    MonitorForm {
        id: monitorForm
        monitorLabel.text: ''
    }
}

import QtQuick.Controls
import QtQuick.Layouts
GridLayout {
    property alias monitorLabel: monitorLabel
    Label { id: monitorLabel }
}