Not having any trouble getting to chapter 1 or playing it up until the trial.

Bbuuutttt for whatever reason the Rebuttal Showdown doesn't seem to work right for me.

The first Weak Spot, "The Generator" can't be hit at all. I've tried, but it seems like it was (intentionally or accidentally) programmed to just not be a weak spot.

But I also can't slash any of the words most of the time? The Slashing animation has this weird delay and even when I see it overlapping with words or when I try to slash in the moment, it just doesn't cut anything...?
Sometimes I've managed it, but it seems very inconsistent.

Is this a bug or is there something I'm missing here?

I've noticed the same too, it's somewhat more consistent if I slash while it's sped up but I still miss a few. The "The Generator" thing wouldn't stop your progress by the way, it's not the answer thankfully.