QML Text: height can not bind to contentHeight (when triggered by a change of its 'text' property)

1. Create a new project: Qt Quick Application - Empty
2. Use default all along the way
3. Paste the code to main.qml (see attachment)
4. Run the app
5. Click the button
6. See the console, we can see the contentHeight is 16 but the height is 0, which is wrong, because in the code we bind them together

main.qml