Nether Biomes + nether features

I created a biome for the nether and tried to put some trees in it. It didn't work, so I gave up. So I created a tree structure (and others) and using the biome feature, I put them in the nether biome I created but it still didn't work!

Can anyone tell me what I'm doing wrong or what I'm forgetting?
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idk why i can't put images but here's the written
UNDERGROUND DECORATION

nether wasteland (custom biome)

(no conditional additions)

Feature configured with positioning

Characteristic forest rock with block

With a 1 in 3 chance
Repeat Constant integer: 3 times
With random XZ inside the chunk
On the Non-air block height map (worldgen)