Property substituted with 0 in QML

Mark81

I'm facing an annoying problem. I'm editing a QML file, here an extract:

Rectangle {
    id: root
    visible: true
    color: "black"

    readonly property int xText: 100
    readonly property int yText: 210
    readonly property int fontSize: 96

    FontLoader {
        id: myfont_bold
        source: "qrc:/font/MyFont Bold.ttf"
    }

    Text {
        x: xText
        y: yText
        color: "white"
        horizontalAlignment: Text.AlignRight
        font.family: myfont_bold.name
        font.pixelSize: fontSize
        text: "30"
    }
}

When I move away from line font.pixelSize: fontSize or even just compile, the editor changes this line to:

font.pixelSize: 0

This doesn't happens every time, but quite often. What's wrong here?
I'm using Qt5.11.1 and QtCreator 4.8.1.

UPDATE: I've just discovered it replace also literal values, like font.pixelSize: 96. In this case the "edited" line is quite weird:

font.pixelSize: 966

or

font.pixelSize:96

or something else...