Here's what I did:
I researched the path that I should have taken through the quest chains and just "retraced" my steps. First, I went to Golden Pagoda and made sure I had done all the quests there. Then I went to The Ruins of Guo-Lai - no NPCs there, and no quests. I did notice some Shao-Tien Precursors wandering around, and decided to kill a few (that's one of the quest objectives). As soon as the first one died, the NPCs phased in at the little camp in Guo-Lai - and two quests became available!
Not sure if it was waiting there long enough or killing the mob, but something triggered a change in phase for me. I'd suggest just "walking the quest chains" again, retracing your steps, and waiting a while in each area for "phasing" to catch up with you.