Alva at Jiquani's Machinarium after retrieving Large Soul Core - Act 3

Alva appears again at Jiquani's Machinarium in front of the Stone Altar (closed) waiting for you to retrieve a Small Soul Core to open the door, even after completing the quest to kill the boss at Jiquani's Sanctum and retrieve the Large Soul Core.

I have the quests "The Trials of Chaos" and "Legacy of the Vaal" currently active. Blackjaw is still alive.

I'm facing the same problem.