Zombies not dropping Carrots

The device I am using is an iPhone 8 Product (RED), but it wasn't an option. My problem is simple. Zombies won't drop carrots. I researched what are the chances of them dropping carrots and the official minecraft wiki said there was a 2.5% chance of them dropping one. I've been farming on a spawner for hours and they have dropped none. They have dropped more iron and shovels. I hope you can resolve this issue quickly.