Sharing this since I couldn’t find a clear answer before flying.
Had an award ticket HKG to LHR in CX business. Separate HK Express flight from SYX to HKG with a 2h25 connection. Everything I read said I’d have to self transfer, collect bags, clear customs, and recheck before CX’s 1 hour cutoff. UConnect only works if it’s on the same itinerary and HKG’s transfer service needed 2.5 hours minimum.
We basically planned for the worst and were ready to just spend time in HK if it failed.
At SYX check in, the agent noticed we were onward in CX business and had a tight connection. She offered to check the bags through since they’re under the same group. Totally unexpected.
Ended up with a smooth transfer and time at The Pier instead of running around landside.
Just putting this out there in case anyone else is in the same situation. Might depend on the station and agent, but it worked for us.