Hey Fana,
I tried to minimize the players affect on the zombies from behind the fence in the new update 1.0.4. Not sure if this fixed this problem yet.
Please let me know if you find any other issues too,
Rafi
Viewing post in bug: hit zombies jump through fence
Rafi,
If I'm understanding Fana correctly, they were OUT SIDE of their base, and hitting zombies through the fence and INTO the base. I believe it's a collider issue, as I actually just saw this happen with a car slamming zombies into a wall and them popping through it.
Fana,
Thanks again for bringing this to our attention!
-Andrew