Order by ignored - is it a bug?

Question

Hi all
In a very simple the order-by clause is ignored, which seems a rather embarassing bug to me if it reall is one.
Can anyone explain the effect?
Thanks a lot
Franziska
-- ordered as expected:
select
  hash
  , anzahl
from
  (select
    hash
    , count(*) as anzahl
  from
    faelle_human_alle
  where
    abgerechnet_11xxx = 1
  group by
    hash)
order by
  anzahl desc
HASH     ANZAHL
51E3104E8DC14051921CEFCA47225341     2400
0BE3E36F76F28DDF1A7B5423CD8D8B7F     2086
AB0571E09D6ADDDA31D81E95F09F0896     1085
EBD225DA0FDB8EDCED055245AAAF3BD4     435
77E818573395A219B3A0978A9B53BA5D     418
63C72D3ACCFFE35CB7AF2363E487E0E0     411
2C920037095C10A57B680C3D39EF6080     388
180B9083BC382FC377EA597EFE1AECD7     382
ID     PID     Operation     Name     Rows     Bytes     Cost     CPU Cost     IO Cost     Temp space     IN-OUT     PQ Dist     PStart     PStop
0          SELECT STATEMENT          268K     9427K     8674      1G     8070                                
1     0       SORT ORDER BY          268K     9427K     8674      1G     8070      32M                         
2     1         HASH GROUP BY          268K     9427K     8674      1G     8070      32M                         
3     2           TABLE ACCESS FULL     FAELLE_HUMAN_ALLE     506K     17M     5526      883M     5138
-- unordered
select
  hash
  , anzahl
from
  (select
    hash
    , count(abgerechnet_11xxx) as anzahl
  from
    faelle_human_alle
  where
    abgerechnet_11xxx = 1
  group by
    hash)
order by
  anzahl desc
HASH     ANZAHL
213145AC4A58A12E48F49B39A5EA6B82     47
665F009B4EB344C65AD16234A50EE7D1     39
05FADA880F690A52DE6B85026BCAD40C     6
338D6128E1E4DCDA6900506E280628CF     6
EF6553A6953CAAB06166BCF1FD456C00     41
A3FBC4D601F5E54DF6899BD0211584B7     4
8154F2F79A8B193710C38479EACC46C3     3
97239839CEC21967515DAC75C004B815     36
ID     PID     Operation     Name     Rows     Bytes     Cost     CPU Cost     IO Cost     Temp space     IN-OUT     PQ Dist     PStart     PStop
0          SELECT STATEMENT          268K     9427K     8674      1G     8070                                
1     0       HASH GROUP BY          268K     9427K     8674      1G     8070      32M                         
2     1         TABLE ACCESS FULL     FAELLE_HUMAN_ALLE     506K     17M     5526      883M     5138
-- also fine:
with x as
(select
    hash
    , count(abgerechnet_11xxx) as anzahl
  from
    faelle_human_alle
  where
    abgerechnet_11xxx = 1
  group by
    hash)
select
  hash
  , anzahl
from
x
order by
  anzahl desc
;                   

Answer 1

Odd!
The only difference I spotted between the first and 2nd queries was the count(*) vs the count(column), which should not have affected the order by clause. The difference in results is probably due to the count(*) accepting nulls.
Could there be an invisible character in the text of the second query causing the ORDER BY clause to be ignored? Can you type the 2nd query in from scratch and see if the error persists (this is unlikely but I can't think of anything more promising right now)?