So, finally got around to do the Heist mission and.. well, did it twice actually so noticed something. (Did it because after I done it I found out I missed picking up certain things, due to the scan did not highlight things all the time during this mission.) In any case, this is what happened.
First time I silently took out everyone at the first floor, part for those at the last Elevator, couldn't find a way to separate those three, so ended up in a shoot out. No problem though. So went down with the elevator and silently took out those three guards left there. Then escaped.
Second time, managed the first floor just fine, since the last three guards actually ended up being separated far away from each other. So maybe a glitch first time ? Although not that important and not what I was curious about. Now, took the elevator down and bang, even before doors opened we were in combat. So was like.. hmm strange. Three reloads and each time in combat so went with it. But then, and this is what I'm wondering if you all had as well, there was also a armored robot down there that made it all much harder ! So, did you all have one of those as well ?