I noticed another thread similar to this but the title was misleading. Currently, the event titled "Defend the Zephyrites from the Branded" is bugged in Thunderhead Peaks thus obstructing progress towards the achievement "Visions of Thunderhead Peaks" needed for the achievement "Vision I: Awakening." From my sources, other players who faced the problem, which has been ongoing since August of this year, the only way to progress the achievement is to get into a different instance of the map which is a rare occurrence since the map rarely fills. The two ways I was recommended to do this was wait until evening in NA time zones or wait until weekly reset, 3am EST currently (It's either 3am or 4am I can't remember.) The IP that is bugged is 22.214.171.124:0. Whether you are having this problem or not, please submit a ticket to ArenaNet because this bug obstructs a legendary item that many have put countless hours and gold into.