Random beaches biomes generating in the middle of plains biome

Put the summary of the bug you're having here

What I expected to happen was...:
Plains biome generating consistently and seamlessly   

What actually happened was...:
A Plains biome covered with beaches in the centre 

Steps to Reproduce:
1. Generate a random seed world with all experiments enabled. (Seed of affected world: -2523171345867653622)
2. Open the world and find incorrect generation