Qt remove row from custom QAbstractListModel does not work

Question

In the following you'll find my custom model. I reduced it to the just necessary things:

class myClass : public QAbstractListModel
{
    Q_OBJECT

    enum Role {
        id=Qt::UserRole,
        call,
        name,
        date,
        time,
    };

public:
    ...

private:
    QList<QJsonObject> database;
    ...
};


...

void myClass::onMQTT(...)
{
    ...
    QJsonObject jsonObject = jsonResponse.object();

    if(database.size() == 8) {
        beginRemoveRows(QModelIndex(), 0, 0);
            database.pop_front();
        endRemoveRows();
    }


    beginInsertRows(QModelIndex(), database.size(), database.size());
        database.push_back(jsonObject);
    endInsertRows();    
}

...

For displaying I use a QML ListView. The displaying works fine. Every time I receive a packet over the network, the onMQTT callback is called and something new is added to the database and it's also displayed in the ListView.

When there are 8 elements in the list, the oldest element shall be deleted and a new element should be added. However, the removing of the rows is not performed. In fact the 8 oldest elements stay visible and nothing new is added. I just see the first incoming 8 messages and that's it. Its not updated at all, although the data in the database is exchanged correctly.