Column sorting on datagrid doesn't work when default grouping on FirstRender is set

I noticed in my own code and in the demo here (Datagrid Grouping API demo (GitHub)) that when there is a default grouping set for when the page first loads (if (args.FirstRender) is true for the datagrid), column sorting doesn't work.

However, if I remove the default grouping and then re-add the grouping, then column sorting does work.

Steps, for the Datagrid Grouping API demo (GitHub):

  1. Upon opening the page, try sorting a column in the grouped datagrid.
    Problem result: the columns don't sort.
  2. Click the X on the "Title" button to ungroup the datagrid.
  3. Sort a column.
    Appropriate Result: The column sorts.
  4. Group the datagrid by the "Title" column again by dragging it to the grouping area.
  5. Try sorting a column.
    Appropriate Result: The column sorts.

Question: Is there a way to get the column sorting working on first render when there is a default grouping on first render?