Grid Layout - A question doesn't take the specified width but is stretched to the full form's width instead

[JaneSjs]

{
  "pages": [
    {
      "name": "page1",
      "elements": [
        {
          "type": "text",
          "name": "question1",
          "colSpan": 1
        },
        {
          "type": "text",
          "name": "question2",
          "colSpan": 3
        }
      ]
    }
  ],
  "widthMode": "responsive",
  "gridLayoutEnabled": true
}

Expected output: question1 takes the 33% width of the entire form's width.
Current output: question1 takes the full form width.