since you also have gathering storm active, i'm guessing isabelle has hidden while you try to lure spinach outside the school — which is why she's not available for you to quest in twisted desire.
the game can't recognize which quest you're currently doing, so this issue happens sometimes. but i have a hotfix for you: https://drive.google.com/file/d/1hQ9tILDO0J_4PCUYMJq0HTswl3zM8twK
please download this file, then drag it to your \AnotherChance-v1.17.1-pc\game folder!