I'm sad to see this heist hasn't been fully corrected since the PTS. There are still guards that seem to make "incomplete" patrols, which means they never go past the relevant hiding spot, allowing you to bypass them. You NEED to step in their blue aura, even if briefly. Speaking of blue aura, these are still sometimes not showing until you go out of hiding and crouch again. Finally, the guards stop at the end of their patrols for FAR too long, making you wait sometimes close to 1 minute until they go back and allow you to get out of your hiding spot and past the guard.
Either increase the timer - providing some room to kill the odd guard or two when their patrols are wasting your time - or revise the guards' behaviour.
Finally, one thing that had never happened to me even on PTS is that on one of my attempts I got transported into a map with no walls, just the floor. I managed to walk around freely, even picked up one of the chests, and it only ended when I finally fell through the floor into a void.