The Marbruk Fighters' Guild building cannot be entered to do the "Prismatic Core" quest. The door is not interactable. All my AD characters of the appropriate level who reached this city are affected. The quest marker first shows on the door to the Mages' Guild rather than the Fighters' Guild. Once I go inside the Mages' Guild, the marker changes to the Fighter's Guild door. But going to that door, it doesn't do anything. There is no option to open it/enter. Reported via /bug in game. Some other people in zone chat reported the same issue, and my husband's account also has the same issue. This completely stops progress for the Fighter's' Guild. Please help.