I get people being disappointed with them leaving out Tysha from tonight's episode but she hasn't been mentioned since what, mid-season 2? I mean, as much of a big deal she is to Tyrion in the books, she kinda becomes an afterthought after Tyrion meets Shae in the TV show. I would be annoyed if she was a big deal in the show but making her a trigger for Tyrion out of nowhere (for the TV show) would only confuse viewers and make it come off as lame for them.
Same with Lady Stoneheart, you can't have such a big reveal come out of nowhere for TV watchers. They should've had a mini plot for the BWB, a couple of cameos and then comeback to them for the finale. Just like with the Tysha stuff, the problem isn't ignoring them for the finale but not building them up for the finale by making TV watchers not forget about them.
That said, I agree this was an underwhelming episode considering the potential it had. I wasn't moved by any of the big reveals and that's a first time with the show