User enters some search criteria to search for any objects (e.g. documents) then selects at least one hit from the result list and clicks Add to Basket. After the selected object is successfully added to the basket the search pane refreshes and wipes out the search criteria that has been entered.
This is a known issue in versions 16.4.2, tracked by (Bentley internal) Defect 1019927.
This issue has been fixed in version 16.7.15.