Vehicle Showcase- Tried to "infiltrate" via multiple angles, AI knows where the player is after the player kills an NPC with a suppressed weapon, even while in cover.
SCUBA Showcase- Able to sneak close to car where the AA weapon is, not able to get closer without setting off the alarm. Have also approached from the NW hill towards to car via prone (As this was the only way to complete "stealth" missions in ArmAII: OA, I figured that it may/may not have carried over), AI turns around and knows your position once alarm is set off.
I've also seen other post with AI have "Superhuman vision/x-ray" vision and I believe that is present as well.