Basic Search: Search by Contributor on partial name doesn't return results

Overview: Search by Contributor on partial name doesn't return results (bug verified in Bugfest, EBSCO environment, Q4 2018)

Steps to reproduce:

1. Login to FOLIO Snapshot (http://folio-snapshot.aws.indexdata.com) and go to Inventory
2. Select "Contributor" in the "Search" control (to prevent any title matches).
3. Put the full name "Harmon, Daniel E." into the search box and press enter (or click search):
   http://folio-snapshot.aws.indexdata.com/inventory/view?qindex=contributor&query=Harmon%2C%20Daniel%20E.&sort=Title
4. The record "Al Gore and global warming" with contributor "Harmon, Daniel E." is found correctly.
5. Now enter the partial name in the basic search box in first pane: "Daniel E." and press enter (or click search):
   http://folio-snapshot.aws.indexdata.com/inventory/view?qindex=contributor&query=Daniel%20E.&sort=Title

Expected result:
Get all records (including the one found in step 4.) where the contributor has the first name: "Daniel E."

Actual result:
No results - at least that's what was reported in the bugfest environment of January, and later in the Snapshot environment (see old description below)

• - - - - - - - - - - - - - - old description - - - - - - - - - - - - - - -

Inventory --> Select Contributor in the "Search" control.
Search on the known contributor first name doesn't return results.
Searching on "George O." instead of "Head, George O."