Inactive PSXLATITEM translate values showing as "Invalid Value" in drop-down list

We're inactivating the phone method of dispatching Purchase Orders.  The PS_PO_HDR table  field  DISP_METHOD uses translate table PSXLATITEM.   The table had an existing row for dispatch method "PHN"   which was active  with an effective date of 01/01/1900.    Via App Designer I inactivated that translate value effective 03/16/2017.   Now there are 2 rows for PHN on the translate table - one active beginning 01/01/1900   and one inactive beginning 03/16/2017. 

When displaying old purchase orders created prior to 3/16/2017 dispatched via phone,  the drop-down box for dispatch method in the PIA   ( path

Purchasing => Purchase Orders => Add/Update PO )  shows "invalid value".     We bounced the application server and cleared the cache after the update and still get the same result.    We would like to have old purchase orders show the correct dispatch method from PS_PO_HDR at that time but want phone to not appear as a valid dispatch method to select for future purchase orders.   Is this not possible, considering this table has an effective date field?