when using TI in following sql it works just fine to get a list of columns for last expression
with a as
(
select distinct object_type from user_objects
)
select distinct a.object_type, a.
from a
once I have union in it (see below), TI list of columns is empty.
with a as
(
select distinct object_type from user_objects
union all
select ‘aaaa’ from dual
)
select distinct a.object_type, a.
from a