You might want to check the bug report system to see if there's something related.

Can you check with 5.10 ? Seems to work correctly

Well, of course I could do that, and from what you wrote, it seems to work there.

But then, I don't really understand the point of releasing the patch release 5.9.4, if in addition to solving bugs, introduces new ones, such as this one...

EDIT: Just checked: it works correctly in 5.10

The mainwindow.ui form contains a single QTreeView item, named treeView, and two buttons named upButton and downButton.

I can confirm that the the problem occurs with 5.9.4 but not in 5.9.2.

dragstandarditemmodel.h:

#ifndef DRAGSTANDARDITEMMODEL_H
#define DRAGSTANDARDITEMMODEL_H

//#include <QAbstractItemModel>
#include <QStandardItemModel>


class DragStandardItemModel : public QStandardItemModel
{
    Q_OBJECT

public:
    DragStandardItemModel(int rows, int columns, QObject *parent = Q_NULLPTR);
    bool move(int from, bool isUp);
};

#endif // DRAGSTANDARDITEMMODEL_H

dragstandarditemmodel.cpp:

#include "dragstandarditemmodel.h"

#include <QDebug>

DragStandardItemModel::DragStandardItemModel(int rows, int columns, QObject *parent)
    : QStandardItemModel(rows, columns, parent)
{

}

bool DragStandardItemModel::move(int from, bool isUp)
{
    //range checking etc.
    const int numRows = rowCount();

    if (from<0 || from>=numRows || (from==0 && isUp) || (from==numRows-1 && !isUp))
        return false;

    const int to = isUp ? from - 1: from + 1;
    const int toSignal = isUp ? to : to + 1;

    if (!beginMoveRows(QModelIndex(), from, from, QModelIndex(), toSignal))
        return false;

    blockSignals(true);

    QList<QStandardItem*> fromRow = takeRow(from);
    beginInsertRows(QModelIndex(), toSignal, toSignal);
    insertRow(to, fromRow);

    blockSignals(false);

    endMoveRows();

    return true;
}

mainwindow.h:

#ifndef MAINWINDOW_H
#define MAINWINDOW_H

#include <QMainWindow>

class DragStandardItemModel;

namespace Ui {
class MainWindow;
}

class MainWindow : public QMainWindow
{
    Q_OBJECT

public:
    explicit MainWindow(QWidget *parent = 0);
    ~MainWindow();

private slots:
    void on_upButton_clicked();
    void on_downButton_clicked();

private:
    Ui::MainWindow *ui;
    DragStandardItemModel* m_colModel;

    void moveCurrentRow(bool isUp);
};

#endif // MAINWINDOW_H

mainwindow.cpp:

#include "mainwindow.h"
#include "ui_mainwindow.h"

#include "dragstandarditemmodel.h"

#include <QStandardItem>

MainWindow::MainWindow(QWidget *parent) :
    QMainWindow(parent),
    ui(new Ui::MainWindow)
{
    ui->setupUi(this);

    //Create model, fill some data, hide 2nd column
    const int numRows = 10;
    const int numCols = 2;

    m_colModel = new DragStandardItemModel(numRows, numCols, ui->treeView);

    for (int i=0; i<numRows; ++i)
    {
        QStandardItem* itm = new QStandardItem(QString::number(i+1));
        itm->setCheckable(true);
        itm->setCheckState(Qt::Checked);
        m_colModel->setItem(i, 0, itm);

        //Hidden column, to contain the logical index of visual item at i
        itm = new QStandardItem(QString::number(i));
        m_colModel->setItem(i, 1, itm);
    }

    m_colModel->setHorizontalHeaderLabels({"Info"});
    ui->treeView->setModel(m_colModel);
    ui->treeView->setColumnHidden(1, true);
    ui->treeView->setSelectionBehavior(QAbstractItemView::SelectRows);

    ui->treeView->setRootIsDecorated(false);
    ui->treeView->resizeColumnToContents(0);
    ui->treeView->setHorizontalScrollBarPolicy(Qt::ScrollBarAlwaysOff);
    ui->treeView->adjustSize();
}

MainWindow::~MainWindow()
{
    delete ui;
}

void MainWindow::moveCurrentRow(bool isUp)
{
    const QModelIndex index = ui->treeView->currentIndex();

    if (index.isValid())
    {
        const int row = index.row();

        if (m_colModel->move(row, isUp))
        {
            const QModelIndex newIndex = m_colModel->index(isUp ? row-1 : row+1, 0);
            ui->treeView->setCurrentIndex(newIndex);
        }
    }
}

void MainWindow::on_upButton_clicked()
{
    moveCurrentRow(true);
}

void MainWindow::on_downButton_clicked()
{
    moveCurrentRow(false);
}

For now, I just re-hide the column after each move, by adding the following line before the setCurrentIndex() operation:

ui->treeView->setColumnHidden(1, true);

But this is just an uggly temp workaround.

Can you show a minimal compilable version that can reused to test that behaviour ?