Zombies spawn stuck in grass path/farmland

In any other version i have played when you fence off and light up a village all zombies spawn outside of the village allowing the villagers to be safe. I have an average light level of 10 in my fenced off village and yet i have zombies spawning in and they are stuck in the ground. This of course only happens when its night out. Ive dug all around thinking maybe there was a zombie spawner close the the surface under my village but i have come up empty handed. There does not appear to be any trigger for this bug. The world i am working in is creative.