Admittedly, not the best mission to start with since I haven't played for over a year, but this mission is doing my skull in. Maybe it is because I am level 50 but I seem to be unable to avoid aggro.

On some of the cameras, there seems to be no way to predict the enemy movements and no matter how clear I am, some mob seems to spot me through terrain from half the map away. I can't kill anything silently since even melee doesn't one-shot. Worse still when I decide 'sod it, I'll just kill them all and do the job', it often seems that I NEVER go back into disguise mode so I have to die and reset all the cameras I already did.

Any advice/help here, please?