Column sorting doesn't work for order results

Overview: When viewing the PO search results (on the orders app landing page), the column sorts don't work.

Steps to Reproduce:

1. Log into FOLIO-snapshot as diku_admin
2. Go to the Orders app
3. You'll see some orders in the middle pane, with columns for PO number, Status, and Created.
4. Click on any of the column headers to re-sort the search results

Expected Results: results should sort ascending or descending when you click the column header

Actual Results: they don't. The up/down arrow appears, but results are not re-sorted,