Not sure if this is a bug or not... and its nothing too serious. But there's a visible light blue trigger in one of the webbed wood tunnels that does nothing as far as I can tell. It is either not functioning as intended or should be invisible if its meant to trigger under certain conditions.
If this is the trigger I think it is, it should be the trigger to a hidden trapdoor, which neither can be used. It appears when you spot it, but you can't actually climb down it.