datagridview click event and drag and drop togeder doesn't work - winform

Question

I've implemented this simple drag and drop between rows of a DataGridView by following this example: datagridview-drag-and-drop-rows

The grid has a checkbox column (DataGridViewCheckBoxColumn) that is no longer clickable after the drag and drop has been implemented.

Maybe the events MouseMove and MouseDown bypass the checkbox's click, so I have tried to intercept the position of the mouse and get a reference to the underlying control (the checkbox) and check it programmatically, but without any success.

private void dataGridView1_MouseDown(object sender, MouseEventArgs e)   
 {
    if (e.Button == MouseButtons.Left)
            {
                Control dgrid = sender as Control;
                Point now = dgrid.PointToClient(Cursor.Position);
                foreach (DataGridViewCheckBoxCell c in dgrid.Controls.OfType<DataGridViewCheckBoxCell>())
                {
            //check if the point is inside the area

        }

    ...other drag&drop operations
 }

But the dgrid.Controls.OfType<DataGridViewCheckBoxCell>() seems to not have any cells inside (obviously there are many)