I have the same issue, and I tried reinstalling the game.
I'm no code expert, and I don't know if I merged any files, If so I did it by accident.
I tried starting a new game and did everything again, but then got the same popup.
I did not delete my old saves though.
Might just be a bug? I did also try to not interact with kate since on my old save I went through all her riddles.