That happened in my case, I had a ticket to TPE and was on a separate ticket to HKG. I would've preferred if CX allowed me to complete OLCI but told me to pick up my BP at desk (after docs check) (similar to HKSAR leaving HKG for TPE). Stopping me from completing OLCI forced me to essentially lie to OLCI, just to get it to complete and give me my seat assignment (I don't need it, but my travelling companions do).