Toad for Oracle 12.11. The index hint itself is off 1 space. The first slash of the index hint should align with the stacked columns below it, so in the example below, the slash should be above the letter "d" (first character of first stacked column) and not “a” the second character.
The example below can show the issue when formatted in TFO 12.11.
/* Formatted on 09/22/2017 1:47:40 PM (QP5 v5.313) */
SELECT /*+ INDEX(who_xtrn who_xtrn_ix1) */
date_time_stamp,
continuation,
user_id,
part_nbr,
ord_id,
trns_code,
trns_data,
rev_cd
FROM who_xtrn
WHERE ord_id LIKE 'SL00092617%'
AND trns_code LIKE 'S%'
AND run_date >= SYSDATE - 3