So I transported over 1200 passengers (around 1260 approximately) in Sao Paulo only using loops. However I didn’t get the achievement notification and the profile says it’s still locked. I tried to think of possible reasons but can’t think of any except for glitch.
There’s a possibility that you broke off 1 loop as you are making new loops or extending loops, and that cut off leads to the achievement staying locked. It is a possibility though, but if you can upload your game session log (the log file for the game session), then the developers can take a look at it to determine what may cause it to stay locked.
Otherwise, we don’t have anything to check the problems with.