Customizing CheckBox example code seems not being working as expected

I'm not sure if it's Qt's issue or documentation issue.

I just copied the code snippet and executed it.

When I hovered over the customized checkbox, it showed the default checkbox(blue check box), which I don't think is an expected behavior.

As far as I could see, there's nothing wrong with the code itself, but since I'm still new to Qt, it might be a mistake in the code snippet in the document.

At the same time, it's also possible that it's a Qt issue and there's nothing wrong with the code snippet.

https://doc.qt.io/qt-6/qtquickcontrols2-customize.html#customizing-checkbox