So, I haven't had the Stick of Truth for very long (Steam says I've only put in 7 hours, bought it the first day of the Summer Sale). When I was doing Jimmy's quest to get the flute (I forget the mission's name, sorry), the new kid began flashing on/off the screen, while Jimmy stayed there. Toward the end, the new kid never came on screen, and Jimmy was gesturing to a phantom.
It's worsened now, I just began the mission to infiltrate the "Taco Bell" (immediately after learning the Sneaky Squeaker from Randy), and the entire cutscene you have before the first Nazi Zombie you find (where he takes out the two SWAT units), everything was flashing besides the background. Even the dimmed lights flashed to make a brighter room.
I've tried the "Validate integrity of game cache" button already.
GPU: Nvidia GeForce GTX 960M 2GB memory
CPU: Intel® Core i7-6700HQ CPU @ 2.60GHz (8 CPUs), ~2.6GHz
DirectX Version 12
OS: Windows 10 Home 64-bit
I.. don't think there's any more info you'd need to help me diagnose, but feel free to ask.