[Knockout] Multi-Select Matrix - The totalText property doesn't work

[JaneSjs]

The totalText property should specify a caption for the total row. However, I see that the total row doesn't have any title.
View Knockout Demo

{
 "pages": [
  {
   "name": "page1",
   "elements": [
    {
     "type": "matrixdropdown",
     "name": "question1",
     "columns": [
      {
       "name": "Column 1",
       "cellType": "text",
       "totalType": "sum",
       "totalDisplayStyle": "decimal"
      }
     ],
     "choices": [
      1,
      2,
      3,
      4,
      5
     ],
     "rows": [
      "Row 1",
      "Row 2"
     ],
     "totalText": "Total"
    }
   ]
  }
 ]
}

It works in React (View Demo).