Game has some serious issues with vertical terrain. I've noticed soldiers will see me through walls and Sahelanthropus can occasionally send his beam through mountains which is really frustrating. Had a section where he slow motion jumps at me and there was no way for me to see Mantis through the rocks and died.
I noticed guards could see through walls on the mansion level in Africa. I fultoned a guy out after looking around and checking there was nobody there and the two guys in the lobby at the front of the house saw it despite being inside.