SQL patch created with DBMS_SQLDIAG.CREATE_SQL_PATCH is recognized but ignored

Oracle version 19.15 on a generic Linux server.

An INSERT statement as part of a section of code cannot be edited directly, but we are able to use SQL Patches to change the hint. Current hint looks like:

insert /*+ noappend enable_parallel_dml */ into . . .

but hint needs to be

/*+ APPEND NOPARALLEL */

and the SQL Patch gets created successfully:

SYS_SQLPTCH_01830a0db62e0003

PL/SQL procedure successfully completed.

Hint report says that the SQL Patch was "used", but NOPARALLEL was "unused" and direct load was disabled because I used the NOAPPEND keyword in the hint, and I get the same exact hint report when I add IGNORE_OPTIM_EMBEDDED_HINTS to the patch hint text.