I am looking to book a trip PVG-HKG-SIN; SIN-MNL(stopover)-HKG-PVG on CX;

When I simply search PVG-SIN-PVG, the return trip priced with fare IR99LDAR, however, when I tried to build in the MNL stop over, either with SIN-MNL vai KUL on MH, so SIN-MNL direct on SQ, ITA either priced it with full price J or not showing flights at all. Question is why would it not price with IR99LDAR? As I read the fare rule: it says unlimitd stopover permitted and unlimited transfer permitted, so I thought the additional stop at MNL can be built in? Did I miss anything?

First time trying to do this, really appreciate your help.

Full fare rule here:

Category 8: Stopover restrictions

0 STOPOVERS PERMITTED ON THE OUTBOUND AND UNLIMITED ON THE
INBOUND FARE COMPONENTS AT CNY 800 EACH
IN HKG INBOUND.
CHILD/INFANT DISCOUNTS APPLY.
AND - UNLIMITED STOPOVERS PERMITTED IN EACH DIRECTION AT
CNY 520 EACH EXCEPT IN HKG.
CHILD/INFANT DISCOUNTS APPLY.

Category 9: Transfer restrictions

UNLIMITED TRANSFERS PERMITTED ON THE FARE COMPONENT
FARE BREAK AND EMBEDDED SURFACE SECTORS NOT PERMITTED ON
THE FARE COMPONENT.

Category 10: Combinability

CIRCLE TRIPS NOT PERMITTED.
END-ON-END NOT PERMITTED. SIDE TRIPS NOT PERMITTED
APPLICABLE ADD-ON CONSTRUCTION IS ADDRESSED IN
MISCELLANEOUS PROVISIONS - CATEGORY 23.
OPEN JAWS
FARES MAY BE COMBINED ON A HALF ROUND TRIP BASIS
-TO FORM SINGLE OR DOUBLE OPEN JAWS WHICH CONSISTS OF NO
MORE THAN 2 INTERNATIONAL FARE COMPONENTS AND THE OPEN
SEGMENT AT ORIGIN MUST BE IN ONE COUNTRY. THE OPEN
SEGMENT AT DESTINATION HAS NO RESTRICTIONS
PROVIDED -
THE OPEN SEGMENT MUST BE
-BETWEEN JAPAN/KOREA, REP. OF/KOREA, DEM. PEOPLE'S REP.
OF AND SOUTHEAST ASIA
-WITHIN JAPAN/KOREA, REP. OF/KOREA, DEM. PEOPLE'S REP.
OF OR WITHIN SOUTHEAST ASIA
COMBINATIONS ARE WITH ANY FARE FOR CARRIER CX IN ANY
RULE IN ANY TARIFF.
ROUND TRIPS
FARES MAY BE COMBINED ON A HALF ROUND TRIP BASIS
-TO FORM ROUND TRIPS.
PROVIDED -
COMBINATIONS ARE WITH ANY FARE FOR CARRIER CX IN ANY
RULE IN ANY TARIFF.
OPEN JAWS
FARES MAY BE COMBINED ON A HALF ROUND TRIP BASIS
-TO FORM SINGLE OR DOUBLE OPEN JAWS WHICH CONSISTS OF NO
MORE THAN 2 INTERNATIONAL FARE COMPONENTS AND THE OPEN
SEGMENT AT ORIGIN MUST BE IN ONE COUNTRY. THE OPEN
SEGMENT AT DESTINATION HAS NO RESTRICTIONS.
MILEAGE OF THE OPEN SEGMENT MUST BE EQUAL/LESS THAN
MILEAGE OF THE SHORTEST FLOWN FARE COMPONENT.
PROVIDED -
THE OPEN SEGMENT MUST BE
WITHIN
-WITHIN AREA 3 OR WITHIN AREA 1 OR WITHIN AREA 2
COMBINATIONS ARE WITH ANY FARE FOR CARRIER CX IN ANY
RULE IN ANY TARIFF.
ROUND TRIPS
FARES MAY BE COMBINED ON A HALF ROUND TRIP BASIS
-TO FORM ROUND TRIPS.
PROVIDED -
COMBINATIONS ARE WITH ANY FARE FOR CARRIER CX IN ANY
RULE AND TARIFF.