I've just now 'completed' the level puzzle, not having any prior knowledge of it. I assumed because the Fox was missing from the one side of signs, that was the key. Obviously nothing happened after I pulled the Fox lever. Then I tried the Hawk lever just to see if a failure caused some reaction at least and still nothing, so pulled Snake and Whale afterwards to get any reaction or a reset. After pulling the levers in said order, the floor opened as is supposed to.
Can't be sure if it's a fart in the system or if there is more than one combo to the lock. Continuing on now.