Igloo generating incorrectly

An igloo seems to have generated incorrectly on a world I was playing on the new snapshot 17w48a. I came across a bizarre structure in a snowy biome which appeared to be an igloo without most of its blocks. I tried the same seed in 1.12.2 however it generated fine.

Steps to reproduce:
Create a new world with the seed of -4532388845826010498
Teleport to 224 69 -382

Image attached.