To all you naysayers, please understand that hiccups such as what the OP posted do not have to happen to you in order for them to be real.
As for that part specifically, the part with the first room of Runners and one Clicker, I also had major problems. The Runner who patrols into the room with the desk(s) could not be stealth killed unless I behaved in one specific way. Quickly I would sneak into the room and get behind the desk, remaining completely still as the Runner passed. After he left the room, I would then get behind the little bit of the couch that was available. Then, when the Runner came back, I was able to full-speed-stealth over and take him out. Undetected.
If I moved while hiding behind the desks, or before he left the room, or attempted to stealth up behind him from anywhere besides the couch hiding spot, I would be heard. It was clearly bad programming insisting that the couch was the only path to success, OR, a buggy area.
They aren't randomly 180ing. You're being heard, and I think it's quite realistic that enemies have acute hearing. Personally, I think stealth on survivor is still too easy. You can crouch walk at full speed and human enemies will be none the wiser.
To properly stealth runners on survivor you need to move incredibly slowly. If you're moving incredibly slowly they won't full blown detect you, but will do a sort of "freak out" animation in a certain direction. It is during this animation that you stealth kill them. If you miss you're chance you're best bet is to simply wait till their next pass on their patrol route.
I thought on Survivor mode, if you were crouched and moving faster than a quarter-stick push, you will be detected at close range. Was the whole quarter-stick thing just for standing up/walking?
Great. Just discovered the Clickers in the University CAN hear you if you literally press no buttons or move the anolog stick.
This is unacceptable, as I progress through the story it's becoming more and more like a chore than a fun experience.
Yeah, clickers use echolocation, which theoretically should allow them to detect you, even if you aren't moving. The clicking sound they make is actually the sound waves that they send out, and by the time it takes for the sound wave to return they can tell the distance between them and objects in the environment, creating something of an "image" in their infected minds. So using echolocation they would be able to see your outline, although it is questionable whether the outline itself would cause them to attack (as your post suggests), or if it take something else for them to realize (maybe slight movement, breathing, experience seeing you before, etc).