Have the same issue. Will hear zombies going after someone only to find them coming threw the wall after me or getting stuck in the corner of the building.

I see this alot.
Seen groups of 2 or 3 zombies just standing attacking air. Think it is when a player logouts while being attacked by zombie.

Also can get them to do this while following you if you go around a vehicle.
Zombies need a lot of work.

This really needs to be fixed