Endermen don't drop enderpearls

I started a new world on bedrock edition after the nether update came out. I've killed a good few endermen at this point but none of them dropped a pearl. I wasn't surprised the first time because usually about 1 in 2 endermen drop a pearl, but after killing a few more without any pearls i realised something was wrong. It has only happened in the overworld as i havent been able to find any endermen in the nether yet.