Short version: If your ticket has your title on it (e.g. MS, MR, etc), it might mess with pre-check (at least on AS).
Had my GE on arrival interview the other day. Took about an hour of waiting to be seen, and then the interview took 5 mins (basically went over the questions in my application to see if anything had changed between applying and the interview).
Interview was completed around 1200hrs, received the full approval via email the next day around 0800hrs (~20 hours later).
Went to use my new Known Traveller Number (KTN) with online check-in for an AS flight (booked by QF on a QF ticket) and didn't get pre-check. Went to the counter to figure out if there was something funny with my booking, and turns out AS had the "MR" as part of my actual name on my ticket (e.g. LASTNAME FIRSTNAME MR). I've noticed MR being added to my ticket before, but this was the first time it caused an issue.
At the check-in counter, they played with my booking, removed the MR at the end... and voila — pre-check on the boarding pass!