Question: Did you not bring this up with the check in agent? Was she a china airlines agent or the local staff? Sometimes I have found staff not actually working for CI but checking them in under contract sometimes do not know.

Really I always would make a fuss if not given an invitation, Also check CI website firstly. If there is no Skyteam lounge at that airport you have to insist on the invitation. Also I always keep an eye to make sure the first class stickers go on being an Emerald.

I know it should be automatic but in the real world these things happen. You might get something so it does not hurt trying.