It's a bug in the game - you can't solve detective cases when your pool skill is too high. Try ascending to fix it.
Ha!
So, I already messaged this to Ezandora, but I'll repeat it here for anyone else who looks at this thread. I called the script just now - and it worked fine. So it's only glitching when it's being called by my daily "breakfast" script. I wonder if something weird is happening since it's running immediately after the witchess solver. Maybe something about that choice adventure isn't being exited gracefully? I'll try switching the order of things before running it tomorrow, and see what happens.