Second playthrough on ps5, but

So I completed this a couple of years ago, and reinstalled it a couple of nights ago, mainly for trophies. But I've run into a problem. I've defeated the Tower Knight, collected the soul and got the trophy for not killing archers. But now the fat official is missing. When I approach the fog I get the message to kill the archdemon. I've searched high and low and can't find anything else that I need to do at 1-3.

What am I missing?