Javelin Throwers targeting behind AL Orc Blockade??

I'm not sure if this is an actual problem or not, but I've noticed that the Javelin Throwers are targeting towers behind the Abyss Lord's Orc blockade. I see the javelin pass through the blockade and destroy the tower behind without damaging the blockade. So far I've only see this occur on Throne Room, but I'm sure it has happened before. Any helpful response in clarifying this would be appreciated.