In QListWidget, when an item is selected, the selection model returns empty index set

void AlbumDelegate::paint(QPainter *painter, const QStyleOptionViewItem &option, const QModelIndex &index) const
{
    auto selectionModel = _album->selectionModel();
    bool isSelected = selectionModel->isSelected(index);
    if (isSelected)
    {
        QModelIndexList indexes = selectionModel->selectedIndexes();
         // the list 'indices' is returning empty
    }
}

class AlbumList : public QListWidget
{
    Q_OBJECT
public:
    explicit AlbumList(QWidget *parent = nullptr);
    ~AlbumList();    AlbumItem *itemFromIndex(const QModelIndex &index) const;
};

class Album : public QFrame
{
    Q_OBJECT
public:
    .
    .
    .
    AlbumList *_albumList;
};

class AlbumDelegate : public QStyledItemDelegate
{    Q_OBJECT
public:
    explicit AlbumDelegate(Album *parent, bool checkable);
    ~AlbumDelegate();    

protected:
    void paint(QPainter *painter, const QStyleOptionViewItem &option, const QModelIndex &index) const override;
    QSize sizeHint(const QStyleOptionViewItem &, const QModelIndex &index) const;

private:  
    Album *_album;
};


Album::Album(QWidget *parent) : QFrame(parent), ui(new Ui::Album)
{
    ui->setupUi(this);
    _albumList = ui->albumList;    
    _delegate = new AlbumDelegate(this, true);
    _albumList->setItemDelegate(_delegate);

}