sql - why doesn't the query engine know this???

so I have a bill of material query (parent, child) joining to a item
master file (twice, once on parent, once on child) and a status file(
joined on parent)... I want the list ordered by parent...

select parent,child,t02.desc,t03.desc,osipo# from
plan_bill t01
join items t02 on t02.item = t01.parent
join items t03 on t03.item = chlid
join ordstatus t04 on ositm# = t01.parent
where
parent like '%MTG%' and
child like 'S%' and
osid = 'OS'
order by bprod ;

I have built all advised indexes, and when I run it takes 30 minutes to
return 800 records.
however, when I take off the order by, it runs in 2 seconds.
then, I tried: (parens around select statement)

(select parent,child,t02.desc,t03.desc,osipo# from
plan_bill t01
join items t02 on t02.item = t01.parent
join items t03 on t03.item = chlid
join ordstatus t04 on ositm# = t01.parent
where
parent like '%MTG%' and
child like 'S%' and
osid = 'OS' )
order by bprod ;

and that ran in 2 seconds...