The Trial of Lingering Pain: one of the levers doesn't affect the labyrinth

One of the levers in the Trial of Lingering Pain (found on the Atlas maps) doesn't affect the labyrinth.
You can proceed without even touching it.
I presume that it could be a feature, however, it seems to be a bug because usually you have to use all the levers to open the door to the next part of the lab.