After completing the Kalimdor Cup Circuit event quest, the map shows the turn-in location near the flight master in Orgrimmar where I picked it up, but the NPC is not there. I had to go to Valdrakken to turn it in.
Same thing in Stormwind.
I’m experiencing the same issue. Can see the turn-in icon on my mini-map if I fly away, but as I get close it disappears.