Versions:
Minecraft: 1.20.1
Forge: 47.3.4
NatProg: 2.3.8

Logs:
https://gist.github.com/CraftyZombie/9421a63acb2cf36d08ef30413d7bb286

Config:
Unaltered.

Description:
I've noticed that in 2.3.8 (I don't remember about 2.3.7), pebbles and twigs will only spawn underwater. I've checked everywhere for them. The rest of the world is completely barren. Downgrading to 2.3.6 makes pebbles spawn elsewhere again. There's no way it's a coincidence, but I don't know the cause of it either.

The exact same issue here as well. Reverting to 2.3.7 fixes the no pebble world generation issue.

The same error happens to me, Pebbles and twigs are not generated on the surface and only under water.

also experiencing the same issue. All pebbles / twigs only exist under water.

Forge / 1.20.1-47.3.7

If I downgrade to 2.3.7 there is a conflict with Silent Gear where even when the Tool Neutering is set to "False" it neuters the Silent Tools.

Chiming in since I just came across this issue as well. I expect the issue stems from this commit that was part of 2.3.8: 5eb0c26

The Utils.inNonWaterFluid method is used in the worldgen for pebbles and twigs, and the logic got reversed when going from .liquid() to .getFluidState().isEmpty().

Thanks a ton @kaiserczar ❤️ merged, closing this ticket -- new release later today with this fix.