Jiquani machinarium

i've started a new run with the with after the the last patch, now i've been arrived to jiquani machinarium, i've joined a party to speed the precess of finding the core and bla bla bla, but when i joined they have finished the scenario and now i'm stuck in jiquani machinarium without the possibility to restart it or going further in jiquani sanctum, because i don't have the quest, i can't start the quest because the altart is already occupied.