QAbstractItemView : cannot drag non-selectable items

#include <QApplication>
#include <QAbstractItemModel>
#include <QListView>
#include <QMimeData>

class Model : public QAbstractItemModel
{
public:
    Model(QObject* parent = nullptr) : QAbstractItemModel { parent } { }

protected:
    virtual QModelIndex index(int row, int column, const QModelIndex &parent) const override
    {
        if(row >= 0 && row < 2)
            return createIndex(row, column);
        return { };
    }

    virtual QModelIndex parent(const QModelIndex &index) const override
    {
        return { };
    }

    virtual int rowCount(const QModelIndex &parent = QModelIndex()) const override
    {
        return 2;
    }

    virtual int columnCount(const QModelIndex &parent = QModelIndex()) const override
    {
        return 1;
    }

    virtual QVariant data(const QModelIndex &index, int role = Qt::DisplayRole) const override
    {
        if(role == Qt::DisplayRole)
            return QString("%1selectable -> %1draggable").arg(index.row() == 0 ? "" : "not ");
        return { };
    }

    virtual Qt::ItemFlags flags(const QModelIndex &index) const override
    {
        if(index.row() == 0)
            return Qt::ItemIsEnabled | Qt::ItemIsSelectable | Qt::ItemIsDragEnabled;
        else
            return Qt::ItemIsEnabled | Qt::ItemIsDragEnabled;
    }

    virtual QMimeData* mimeData(const QModelIndexList &indexes) const override
    {
        return new QMimeData();
    }
};

int main(int argc, char *argv[])
{
    QApplication a(argc, argv);

    QListView view;
    view.show();
    view.setDragEnabled(true);
    view.setDragDropMode(QAbstractItemView::DragOnly);

    Model model;
    view.setModel(&model);

    return a.exec();
}