Hello, just completed Tixx’s Infinirarium. After completing it, and opening a chest a guildy joined the instance with a another character to clear the town for the achievment, but noticed the chest was still on his map, he could also open it. Another party member tried this and confirmed it works.
Kaname Tanuma – 80 Necromancer
Far Shiverpeaks – Bubblegum Dragons [GUM]