fonts not loaded on certain Windows 10 systems

[franzhelmut]

My application includes this list of fonts as a qrc.
They are used in QML code, but on certain Windows 10 systems with very tight security there are no fonts displayed at all in the GUI.

FontLoader {
    id: robotoBold
    source: "qrc:/assets/fonts/Roboto-Bold.ttf"
}
FontLoader {
    id: robotoMedium
    source: "qrc:/assets/fonts/Roboto-Medium.ttf"
}
FontLoader {
    id: robotoLight
    source: "qrc:/assets/fonts/Roboto-Light.ttf"
}
FontLoader {
    id: robotoRegular
    source: "qrc:/assets/fonts/Roboto-Regular.ttf"
}