If you have a zombie chasing you and you run into a building that has steps going into it making the first floor higher than the ground. The zombies will run through the building but still on the ground. So they are glitched and you can only see half of their body and can still freely hit you.
I ran into the military building that has a jail cell and went to the second floor hoping to escape the glitched zombie but even though it was glitched in the first floor. It still hit me and killed me while on the second floor.