OpacityMaskItem running on raspberry pi

[PieterW_]

I have an application for the RPI which uses a custom progress bar made with an OpacityMaskItem. Everything compiles and runs perfectly when I tell my Ubuntu development PC to run it on the RPI. However, when the app is ran directly from the RPI the progress bar is not displayed. It seems as though the opacity mask suddenly fails to be displayed.

        OpacityMaskItem {
            id: opacityMask1
            x: 244
            y: 78
            width: 320
            height: 320
            invert: false
            Item {
                id: item1
                width: 320
                height: 320
                Image {
                    id: progress_png
                    x: 0
                    y: 5
                    source: "assets/prog.png"
                    fillMode: Image.PreserveAspectFit
                }
            }
            ArcItem {
                id: arc
                x: 0
                y: 0
                width: 320
                height: 320
                end: 145 //140
                begin: -142
                strokeWidth: 30
                strokeColor: "#ffffff"
                fillColor: "#00000000"
            }
        }