Are you guys using retail version by any chance? is there also a specific location that certain cheat won't work?
Undetected doesn't work for now.
It's working just fine you are the only one with issue so far so with more details in description of the problem would be appreciated in future, by the way you might have to use carefully that cheat, while on, you can pretty much do anything in bounders but if you do something unexpected action triggers like killing in front of people, using combat as well etc . NPCs will eventually freak out and getting crime status notice but alert won't go off but it will if you try to turn off for something you may need, in this case, achievements or rather challenges.