QML Preview: Updates to Singletons do not reflect in the preview

Code

import QtQuick
import SingletonTest

Window {
    width: 640
    height: 480
    visible: true
    color: ConstantsSingleton.col

    ConstantsInstantiable { id: ci }

    Rectangle {
        width: 100
        height: 100
        anchors.centerIn: parent
        color: ci.col
    }
}

Steps to reproduce

1. Load the attached project in Qt Creator
2. Open Main.qml and select "Build" > "QML Preview"
3. Open ConstantsInstantiable.qml and change the value of col to a different colour
4. Open ConstantsSingleton.qml and change the value of col to a different colour

Outcomes

• Step #2: The preview window appears (Expected)
• Step #3: In the preview window, the central square changes to your new colour (Expected)
• Step #4: In the preview window, the window background remains the old colour (Not Expected)

Other Notes
Even though the final result is ignored, the intermediate values in ConstantsSingleton.qml do affect the preview as described in QTCREATORBUG-32409. In the middle of doing Step #4, the preview window disappears and the General Message pane shows this:

Error loading QML Live Preview:
qrc:/qt/qml/SingletonTest/Main.qml:9 Type ConstantsInstantiable unavailable
qrc:/qt/qml/SingletonTest/ConstantsInstantiable.qml:-1 Type ConstantsSingleton unavailable
qrc:/qt/qml/SingletonTest/ConstantsSingleton.qml:5 Invalid property assignment: color expected

(I'm not sure why it's complaining about ConstantsInstantiable which is in a good state - ConstantsSingleton is the one that contained the invalid colour string)