A lot of people in the mayhem event are reporting that they have had a bug where nothing can be activated: light/heavy attacks, magic or stamina skills etc. reloadui and pvp or pve death doesn't fix it. The only way is to visit cheesemongers grotto i.e another instance. This is another game breaking bug. we are no further forward to fixing many bugs that have existed for a decade i see no reason to celebrate this 10 year event.