There seems to be something common with all ZC Builds on any overworld screen. If you build a screen so that the edge has nothing, but the next column has a solid combo such as a bush, any enemies that spawn in that area find themselves "stuck", and can't move up or down.
I have found proof that this problem doesn't show up on NES Zelda.
...well, okay, it's the famous Outlands hack. Still, it should be a valid reference. Check it here. You want around 3:50 - 3:55 in.