I can see that that after i call dataChanged, the "parent" method is called for the item i want to update. No other methods are called.

I have a Root structure which contains all the items. Root iself is not shown in the tree. As the item i want to update is in Root, the parent method returns empty QModelIndex. I tried to return Root with index 0 but it did not help.

The problem is also visible even if Root is not the parent but another item.

QModelIndex TreeViewModel::parent(const QModelIndex &index) const
{
    qDebug() << "parent called";
    QModelIndex modelIndex;

    if (index.isValid())
    {
        FileData* item = static_cast<FileData*>(index.internalPointer());
        qDebug() << "parent called for: " << item->filename;
        if (item->parent && item->parent != rootItem)
        {
            qDebug() << "parent: " << item->parent->filename << " - " <<item->parent->index;
            modelIndex = createIndex(item->parent->index, 0, item->parent);
        }
    }

    return modelIndex;
}

void TreeViewModel::updateData(FileData *item)
{
    //emit layoutAboutToBeChanged();
    qDebug() << "updateData called";
    QModelIndex index = createIndex(item->index, 0, item);
    emit dataChanged(index, index, QList<int>({DownloadProgressRole, IsDownloadedRole}));
    //emit layoutChanged();
}

In the QML file, inside TreeView i put
rootIndex: manager.modelIndex

which returns the Root item.

Any idea what could be wrong?