Answer
On some update levels, a Navigation Link's destination filter can end up populated with the raw Oracle/database field name instead of the Aurena field name the page's search actually expects — the two aren't interchangeable even though they refer to the same data. The fix is to manually overwrite the NavigateFilter value back to the correct Aurena field name (e.g. CustomerId rather than its underlying database column name) so the destination page's search works correctly again.