Forge version: 1.12.2
Twilight Forest version: 3.10.1013

Steps to reproduce:

1. Unknown

What I expected to happen:
Twilight forest generates normally
What happened instead:
Portal generates alone high up, no terrain generates, only structures.

https://user-images.githubusercontent.com/58450660/84056321-adca2880-a97b-11ea-9ca4-9b740f4dbb40.png

Any idea of a fix, or what mod might be causing it?

Yes this is the skylight forest terrain. Closing as working as intended unless it's found this is generating as so with the config option disabled. (Note, disabling after world generation wont change already generated chunks)

there's a config option "skylight forest" where no land generates, only structures, check you don't have that enabled