Query Rewrite ISSUE (ANSI JOINS do not work, traditional join works ) 11gR2

Question

For some types of queries constructed with ANSI JOINS, materialized views are not being used.
This is currently increasing time on various reports since we cannot control the way the queries are generated(Tableau Application generates and runs queries against the STAR Schema).
Have tried to debug this behavior using DBMS_MVIEW.EXPLAIN_REWRITE and mv_capabilities function without any success.
The database is configured for query rewrite: REWRITE INTEGRITY, QUERY REWRITE ENABLED and other settings are in place.
Have successfully reproduced the issue using SH Sample schema:
Q1 and Q2 are logically identical the only difference between them being the type of join used:
Q1: ANSI JOIN
Q2: Traditional join
Below is an example that can be validated on SH sample schema.
Any help on this will be highly appreciated.
-- Q1: the query is generated by an app and needs to be rewritten with materialized view
SELECT cntr.country_subregion, cust.cust_year_of_birth, COUNT(DISTINCT cust.cust_first_name)
FROM customers cust
INNER JOIN countries cntr
   ON cust.country_id = cntr.country_id
GROUP BY cntr.country_subregion, cust_year_of_birth;
-- Q2: the query with traditional join is rewritten with materialized view
SELECT cntr.country_subregion, cust.cust_year_of_birth, COUNT(DISTINCT cust.cust_first_name)
FROM customers cust
INNER JOIN countries cntr
   ON cust.country_id = cntr.country_id
GROUP BY cntr.country_subregion, cust_year_of_birth;Tested both queries with the following materialized views:
CREATE MATERIALIZED VIEW MVIEW_TEST_1
ENABLE QUERY REWRITE
AS
SELECT cntr.country_subregion, cust.cust_year_of_birth, COUNT(DISTINCT cust.cust_first_name)
FROM customers cust
INNER JOIN countries cntr
   ON cust.country_id = cntr.country_id
GROUP BY cntr.country_subregion, cust_year_of_birth;
CREATE MATERIALIZED VIEW MVIEW_TEST_2
ENABLE QUERY REWRITE
AS
SELECT cntr.country_subregion, cust.cust_year_of_birth, COUNT(DISTINCT cust.cust_first_name)
FROM customers cust,  countries cntr
WHERE cust.country_id = cntr.country_id
GROUP BY cntr.country_subregion, cust_year_of_birth;Explain Plans showing that Q1 does not use materialized view and Q2 uses materialized view
SET AUTOTRACE TRACEONLY
--Q1 does not use MVIEW_TEST_1
SQL> SELECT cntr.country_subregion, cust.cust_year_of_birth, COUNT(DISTINCT cust.cust_first_name)
FROM customers cust
INNER JOIN countries cntr
   ON cust.country_id = cntr.country_id
GROUP BY cntr.country_subregion, cust_year_of_birth;  2    3    4    5 
511 rows selected.
Execution Plan
Plan hash value: 1218164197
| Id  | Operation           | Name       | Rows  | Bytes |TempSpc| Cost (%CPU)| Time       |
|   0 | SELECT STATEMENT      |        |   425 | 12325 |       |   916   (1)| 00:00:11 |
|   1 |  HASH GROUP BY           |        |   425 | 12325 |       |   916   (1)| 00:00:11 |
|   2 |   VIEW                | VM_NWVW_1 | 55500 |  1571K|       |   916   (1)| 00:00:11 |
|   3 |    HASH GROUP BY      |        | 55500 |  1842K|  2408K|   916   (1)| 00:00:11 |
|*  4 |     HASH JOIN           |        | 55500 |  1842K|       |   409   (1)| 00:00:05 |
|   5 |      TABLE ACCESS FULL| COUNTRIES |    23 |   414 |       |     3   (0)| 00:00:01 |
|   6 |      TABLE ACCESS FULL| CUSTOMERS | 55500 |   867K|       |   405   (1)| 00:00:05 |
--Q2 uses MVIEW_TEST_2
SQL> SELECT cntr.country_subregion, cust.cust_year_of_birth, COUNT(DISTINCT cust.cust_first_name)
FROM customers cust,  countries cntr
WHERE cust.country_id = cntr.country_id
GROUP BY cntr.country_subregion, cust_year_of_birth;  2    3    4 
511 rows selected.
Execution Plan
Plan hash value: 2126022771
| Id  | Operation               | Name         | Rows  | Bytes | Cost (%CPU)| Time     |
|   0 | SELECT STATEMENT          |              |     511 | 21973 |       3   (0)| 00:00:01 |
|   1 |  MAT_VIEW REWRITE ACCESS FULL| MVIEW_TEST_2 |     511 | 21973 |       3   (0)| 00:00:01 |
---------------------------------------------------------------------------------------------Database version 11gR1 (Tested also on 11gR2)
SQL> select * from v$version;
BANNER
Oracle Database 11g Enterprise Edition Release 11.2.0.1.0 - 64bit Production
PL/SQL Release 11.2.0.1.0 - Production
CORE     11.2.0.1.0     Production
TNS for Linux: Version 11.2.0.1.0 - Production
NLSRTL Version 11.2.0.1.0 - Production

Answer 1

Thanks for the formatting tips.
Just found an Oracle Bug which explains the above behavior.
Unfortunately the bug will be fixed only in 12.1 Release so as a workaround will try to use traditional joins.
For those who have metalink access see [Bug 10145667 : ERRORS TRYING TO REWRITE QUERY WITH EXACT TEXT MATCH TO MVIEW]