RETURNING after double CTE Insert

Question

I would like to insert some values in this way:

    with first_insert as (
   insert into stacks(press_id,quantita_a,quantita_b,quantita_c) 
   values($press_id, 
   coalesce((select something),-1),
   coalesce((select something),-1),
   coalesce((select something),-1)) 
   RETURNING id_stack,qty_a,qty_b,qty_c
)
insert into stacks_panels_ct(id_stack,panel_read_id) 
  (select id_stack,panel_read_id from pile_wip
join first_insert on true
where press_id=$press_id2 and stack_number=$stack_number)

select qty_a,qty_b,qty_c from first_insert

and at the end of the second insert, I would like to return (for third-party use) the values of qty_a, qty_b and qty_c.

Everything works fine except for the last SELECT, which does not work at all.

Using RETURNING in place of the last SELECT does not work.

I am using timescaledb:2.3.0-pg13 (Timescale 2.3.0 on Postgres 13)

Thanks in advance, Fabio