[1.15.2] - Custom World Gen Feature Placement

[ModMCdl]

Hello. I'm having a very strange issue in regards to feature placement in my custom world gen: specifically mobs and structures. (Decorators work fine). In my custom chunk generator in my dimension, the generation is nonexistent. Structures don't spawn (the /locate command finds them, but nothing is there, and often the locations is not even in the correct biome). My mobs very rarely spawn at all. I have found them, but only once or twice and not nearly as high as they are weighted to spawn. The weird part is, if I create a buffet world with just the biome, everything spawns and generates fine. 

Because of this, I thought that it might be related to my custom chunk generator just not being compatible with Minecraft's placement routines. My chunk gen is an adaptation of the end islands generation, just with more verticality to the islands. So I tested the generation in a buffet world with default end generation, and the spawning/placement again worked fine.

Could anyone possibly take a look at maybe see something that I missed in regards to the generation, or an explanation as to why this might be happening? Thanks.

Structure class at GitHub

Creature Spawns class at GitHub

Entire repo (if you need/want it)