Performance Tuning :: Querying GTT In Parallel Mode

I am inserting data into a global temporary table and then using 'parallel' hint to query from this temporary table. I remember reading that the queries on the temp table may not run in parallel as the parallel sessions may not be able to see the data in the temporary table

However the execution plan as well as px_session, v$sql indicate that the query on the temporary table in fact run in parallel mode

select * from table(dbms_xplan.display_cursor(null,null,'ALLSTATS LAST'));

PLAN_TABLE_OUTPUT
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SQL_ID 7d68g52g0mskz, child number 0
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select /*+ gather_plan_statistics parallel(t,4) */ * from dbo_gtt t order by id,object_id

Plan hash value: 5815349
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| Id | Operation | Name | Starts | E-Rows | A-Rows | A-Time | Buffers | OMem | 1Mem | Used-Mem |Used-Tmp|
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| 1 | PX COORDINATOR | | 1 | | 99999 |00:00:01.46 | 3 | | | |
|
| 2 | PX SEND QC (ORDER) | :TQ10001 | 0 | 1 | 0 |00:00:00.01 | 0 | | | |
|
| 3 | SORT ORDER BY | | 0 | 1 | 0 |00:00:00.01 | 0 | 11M| 1311K| 424K (0)|
|
| 4 | PX RECEIVE | | 0 | 1 | 0 |00:00:00.01 | 0 | | | |
|
| 5 | PX SEND RANGE | :TQ10000 | 0 | 1 | 0 |00:00:00.01 | 0 | | | |
|
| 6 | PX BLOCK ITERATOR | | 0 | 1 | 0 |00:00:00.01 | 0 | | | |
|
|* 7 | TABLE ACCESS FULL| DBO_GTT | 0 | 1 | 0 |00:00:00.01 | 0 | | | |
|
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Predicate Information (identified by operation id):
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7 - access(:Z>=:Z AND :Z<=:Z)

select px_servers_executions from v$sql where sql_text like 'select%dbo_gtt t%';

PX_SERVERS_EXECUTIONS
---------------------
0
4

select sid, qcsid, server#, degree from v$px_session where qcsid = 228;

SID QCSID SERVER# DEGREE
---------- ---------- ---------- ----------
247 228 1 4
196 228 2 4
224 228 3 4
234 228 4 4
226 228 1 4
252 228 2 4
212 228 3 4
229 228 4 4
228 228

9 rows selected.

unfortunately I do not have access to get trace (tkprof) report. What must have happened during the execution?