I am a lvl 68 Ele. I can consistently recreate this bug. When I get to the end of the lvl 60 ‘Under Siege’ personal quest in Gendarran Fields (https://wiki.guildwars2.com/wiki/Under_Siege), I am disconnected from the server and cannot complete the quest (I have to restart the quest again). The disconnect happens after defeating Vizier Ghil Ironghoul.