My wife and I have been sitting in a map all evening trying to get the last piece of the Griffon collection from the Escort Second Spear Nayrim event chain https://wiki.guildwars2.com/wiki/Escort_Second_Spear_Nayrim_to_potential_shelter . After a while the first event (Defend the Town) spawned again. We then waited for another hour except this time completed every single other event in the area even though they aren't marked as [Group Event]. This time the escort event did spawn. EDIT: The last event that seemed it "did it" was the Ogre escort event. I see that there is also this thread on the issue, https://en-forum.guildwars2.com/discussion/comment/1102335#Comment_1102335 , but on a hunch, is it possible that the event isn't implemented as a linear series like the wiki says? Could it have multiple dependent events, some of which aren't marked as [Group Event] ? I'm doubtful that our experience was part of your design intent so hopefully it can be smoothed for others in the future :)