When I was doing the 2 week free version of UWorld, I was able to practice acids/bases on the Gen Chem Section, but now I don't see it. What happened to it? Why was it taken out of the full, paid version if it's one of the most tested subjects?

It's in the solutions and thermochemistry section. They updated the site and fixed some stuff, some parts are less compact. The Behavioral sciences numbering needs fixing too as you can see, it starts with 3,4,... instead of 1,2,3...