Please note that the following passengers can check in online but cannot print their own Boarding Pass:
Passengers who have purchased tickets with fares applicable for infant
Passengers who have purchased air tickets in conjunction with ferry tickets
Passengers travelling on CX745 from Hong Kong to Dubai/Jeddah
https://www.cathaypacific.com/cx/en_...ding-pass.html
I guess it has something to do with the onward leg to Jeddah as CX has another flight to Dubai with no onward flight and can print boarding pass for that flight.