I am also seeing discrepancies between EF and the CX website. Supposedly I am seeing no inventory on EF but am able to find (multiple) tickets in H and R fare class on CX website. EF seach results are below...

Results from ExpertFlyer.com

Flight Availability Search
Departing HKG on 06/19/15 12:00 AM for YYZ
Direct/Non-Stop Only
Point of Sale: UK

Frequency
Flight Stops Depart Arrive Aircraft Reliability Available Classes
0 Connections
CX 828 0 HKG YYZ 77W Su,W,F J3 C2 DL IL W1 R1 EL YL BL HL KL ML LL VL SL NL QC OL
06/19/15 10:45 AM 06/19/15 1:45 PM 52% / 31m

0 Connections
CX 826 0 HKG YYZ 77W Daily J1 CL DL IL W1 R1 EL YL BL H2 KL ML LL VL SL NL QC OL
06/19/15 5:10 PM 06/19/15 8:20 PM 62% / 36m


Results from ExpertFlyer.com

Flight Availability Search
Departing HKG on 06/19/15 12:00 AM for YYZ
Point of Sale: US

Frequency
Flight Stops Depart Arrive Aircraft Reliability Available Classes
0 Connections
CX 828 0 HKG YYZ 77W Su,W,F J3 C3 D0 I0 W1 R0 E0 Y2 B0 H0 K0 M0 L0 V0 S0 N0 Q0 O0
06/19/15 10:45 AM 06/19/15 1:45 PM 52% / 31m

0 Connections
CX 826 0 HKG YYZ 77W Daily J1 C1 D0 I0 W0 R0 E0 Y6 B1 H0 K0 M0 L0 V0 S0 N0 Q0 O0
06/19/15 5:10 PM 06/19/15 8:20 PM 62% / 36m