QPdfBookmarkModel return -1 as page number

VincNRC

I'm currently testing using Qtpdf for reading a pdf. I based my code on the exemple from Qt (https://doc.qt.io/qt-5/qtpdf-pdfviewer-example.html)

For some PDF, when selecting a bookmark from the list, the page number returned is -1. Only the 3 or 4 first elements return the correct page number. I tried opening those pdf on my PC and all the bookmarks work fine on this end. What can be the cause of this?

Here is my code

Pieces::Pieces(QWidget *parent) :
    QWidget(parent),
    ui(new Ui::Pieces)
{
    ui->setupUi(this);
    pdfView = new QPdfView(this);
    m_document = new QPdfDocument(this);
    m_bookModel = new QPdfBookmarkModel(this);

    m_document->load(":/pdf/pdf/8923516.pdf");
    m_bookModel->setDocument(m_document);
    pdfView->setDocument(m_document);
    pdfView->setZoomFactor(pdfView->zoomFactor() / 1.15);

    ui->layoutPartsPdf->addWidget(pdfView);
    ui->listViewBookmarks->setModel(m_bookModel);

    connect(ui->listViewBookmarks, SIGNAL(activated(QModelIndex)), this, SLOT(bookSelected(QModelIndex)));
}

void Pieces::bookSelected(const QModelIndex &index){
    if(!index.isValid()){
        return;
    }

    const int page = index.data(QPdfBookmarkModel::PageNumberRole).toInt();
    ui->label->setText(QString::number(page));
    pdfView->pageNavigation()->setCurrentPage(page);
}