It's actually a combination of peak and the glut of interviews HR is trying to work through right now.
Back in the spring they opened the floodgates on the ACP meet-and-greets, and got overwhelmed to the point where they shut them down about 8 (?) weeks ago. They had enough people to fill interviews/classes through the end of the year.
A class of 16 just started on Monday so interviewing/hiring is still going on, but they are slogging through the rest of the people who bum-rushed the place over the past 6 months.
If you didn't get your meet-and-greet done before the summer, I'd expect to wait until Jan at the earliest for it. Hopefully the turn time from greet to interview will be shortened considerably from (what I hear is) the current 6 months.