I've tried with the begin/endResetModel which is working fine.
I also noticed that the edited field is updating if I hide it thew reshow it by dragging the treeview out of the layer (as the content of the treeview draggable).

I've also tried to send the signal on the root or on the parents.
Things like that :

            QModelIndex rootIndex = createIndex(0, 0, m_root);
            QModelIndex rootIndex2 = createIndex(m_root->childCount(), m_root->columnCount(), m_root);
            emit dataChanged(rootIndex, rootIndex2);

but with no results.

I'm pretty sure there is some subtilty i didn't get but i can't find out so i need your help =)

Here's a simplified version of what i'm doing :
-In my tree model :

bool MapMarkerTreeModel::setData(const QModelIndex& _index, const QVariant& _value, int _role/* = Qt::EditRole*/)
{
    if (!_index.isValid())
    {
        return false;
    }

    if(MapMarkerTreeItem* item = getItem(_index))
    {
        if(item->setData(_value, _role))
        {
//            beginResetModel(); <----- This is working
//            endResetModel();
            emit dataChanged(_index, _index); // <----- This isn't

            return true;
        }
    }

    return false;
}

-Also in my tree model, index and parent methods :

QModelIndex MapMarkerTreeModel::index(const MapMarkerTreeItem* _item) const
{
    QModelIndex index{};
    if(_item != nullptr)
    {
        index = createIndex(_item->childNumber(), 0, _item);
    }

    return index;
}

QModelIndex MapMarkerTreeModel::parent(const QModelIndex& _index) const
{
    if (!_index.isValid() || m_root == nullptr)
    {
        return QModelIndex();
    }

    MapMarkerTreeItem* childItem = getItem(_index);
    MapMarkerTreeItem* parentItem = childItem ? childItem->parent() : nullptr;

    if (!parentItem)
    {
        return QModelIndex();
    }

    return createIndex(parentItem->childNumber(), 0, parentItem);
}

I'm not sure what else I can provide for context, if anything can help please tell me.
And thanks in advance !