No soul sand in soul sand valleys

It seems like soul sand is not spawning in soul sand valleys. The large bones and skeletons are surrounded by nether rack.

Btw, love the new mountains!!

What I expected to happen was...:
That soul sand would spawn in the soul sand valley biome.

What actually happened was...:
I could not find any soul sand in the soul sand valleys after searching them out in a creative world.

Steps to Reproduce:
1. Use world seed: -4363852756553760707 in snapshot 21w37a, in Java edition
2.  Go to the Nether
3.  teleport to soul sand valley at either: [1000, y, 1000] or [-48, y, 12]