Dear Mr. Nygma:
I believe this event does not come online with the server reset, so it is generally not doable first thing in the morning. Sometimes it does not activate until 9:30am or some odd time, which is fairly unique for this event, and it will not activate until a manual refresh of the game is performed, which is why you saw the event activate when you refreshed. The same thing happens if you achieve level 80 at some point later; a manual refresh is necessary to gain access.
Sorry about the trouble!