On chapter 4 I had the same problems too, after playing the previous chapters with no problems. What I found was that at any resolution other than 1920x1080 the contrast dimmed to almost dark. I only was fiddling with the different contrasts due to increased stuttering, jagged edges and lag in movement scenes. I decided to continue to play at that resolution and bear with the frame rate issue but about midway my char walked thru a wall and got stuck out of bounds. Restarting the game saw the chapter reset to beginning.
not a clue what the problem is but they had issued a patch in march to address performance issues, they may have broken some graphic cards instead.
i sent a bug report to their support site:
I found the same happened with me. The contrast settings rendered the game unplayable unless the resolution is set to native (that happens to be the max res of my screen).
Native resolution solves the contrast, but as per your experience, the movement scenes drop to around 4 frames/second.
I'll send an email to the support contact you have in your post.