Scripted event fails in Valves and Pipes

[Cass]

Hi guys,

So I'm walking through the Valves and Pipes section when I'm presented with a fork. Left goes through to a path that's blocked by steam. Right goes through to a path that collapses underneath me, and should deposit me in the sewer water below to be chased by one of the invisible enemies (as shown in this Youtube video of the sequence).

However, instead what happened was that I triggered the event but instead of being deposited into the water, I was instead left back up on the path, able to see the broken walkway, but my right path is now blocked by steam. I can't now progress the game, and because I didn't realise I saved the game almost immediately after. So I'm a bit stuck. Can anyone help?