Not sure how reproduceable and how long it will stay:

"After you grab the parking pass and the cells open up releasing all the zombies, you run into one of the cells and get yourself cornered. You get a bunch of them into the cell for a giant gangbang fuckfest. After 2 bites and your camera going haywire you get i-frames that don't go away."

Im sorry. What is "i-frames"?

Can you show us a video of this?

@PrivateNioo I-frames are invincibility frames, meaning you wont take damage.