GridView / ListView : wrong filling direction with Loader as delegate

import QtQuick 2.5

ListView {
    id: listView
    anchors.fill: parent

    model: ListModel {
        id: data
        ListElement {
            url: "https://images.unsplash.com/photo-1453743327117-664e2bf4e951?ixlib=rb-0.3.5&q=80&fm=jpg&crop=entropy&s=d5447d7f37886d9890d448d0858da12f"
        }
    }

    property bool nextLoaded: false
    function loadNext() {
        if (!nextLoaded) {
            nextLoaded = true;

            var next = [
                {
                    url: "https://images.unsplash.com/photo-1452800185063-6db5e12b8e2e?ixlib=rb-0.3.5&q=80&fm=jpg&crop=entropy&s=2700f9770386e4c5ebc53502a9099966"
                },
                {
                    url: "https://images.unsplash.com/photo-1452274381522-521513015433?ixlib=rb-0.3.5&q=80&fm=jpg&crop=entropy&s=476b9724fcf47b51c652d66e384f9ba0"
                }
            ];

            data.append(next);
        }
    }

    onContentYChanged: {
        if (contentHeight - contentY - height < 1000)
            loadNext();
    }

    delegate: Component {

        Loader {
            width: parent.width
            height: 200
            asynchronous: true
            visible: status == Loader.Ready

            onStatusChanged: {
                if (status == Loader.Ready) {
                    console.log("loader "+index+" is ready");
                }
            }

            sourceComponent: Component {

                Image {
                    source: url
                    cache: false
                    asynchronous: true

                    anchors.fill: parent
                    fillMode: Image.PreserveAspectCrop

                    onStatusChanged: {
                        if (status == Image.Loading) {
                            console.log("image "+index+" is loading");
                        }
                    }
                }
            }
        }
    }
}

qml: image 2 is loading
qml: loader 2 is ready
qml: image 1 is loading
qml: loader 1 is ready