ORA-54008: expression column is not supported for an index organized table

create table tq84_ora_54008(
   pk         integer primary key,
   val        varchar2(10),
   val_up as (upper(val))
)
organization index;

create table tq84_ora_54008(
   pk  integer primary key,
   val varchar2(10)
) organization index;
   
alter table tq84_ora_54008 add (val_up as (upper(val)));