Hi,
I have the same "problem". I haven't been playing for a while but started up again some days ago and I'm quite sure that they didn't run off instantly after diagnosing a desease then, but now they do. I also made sure to have enough leeches at the table.
I read somewhere that it might be connected to the range of free will you give your sims.. but i haven't tested it yet.
Well, if it isn't a bug it sure as hell is an annoying change 😕mileytongue: