OTG Plugin or Mod

[Please specify if it's about Forge Mod or Spigot server Plugin placing "x" into []]

• [X ] OTG Mod for Forge
• OTG Plugin for Spigot

OTG Version

[Please specify the full OTG version that you are running by placing "x" into []]

• 1.12.2_v8_r1
• 1.12.2_v7_DEV_r26
• 1.12.2-v6
• 1.12.2-v5
• 1.11.2-v8
• 1.11.2-v9
• 1.10.2-v21
• [ X] Other - 1.16.5

Forge or Spigot Versions

[The full Spigot Server or Forge versions that you are running]
N/A

What other plugins are you running?

[List of your Mods or Plugins installed, ideally with versions]
AI-Improvements 1.16.2
AmbientEnvironment
AE 2
architectury
AutoReLib
BiomesOPlenty
Bookshelf
Botania
Builders Addition
chiseled
chisels and bits
citatdel
Clumps
cofh_core
constructionwand
Controlling
CraftTweaker
curios-forge
Cyclic
DamageTilt
DoubleSlabs
envirocore
envirotech
extlights
FastFurnance
FastLeafDecay
FastWorkBench
ftb-gui-library
GameStages
ice&fire
ironchest
jei
journeymap
lighting wand
mcw-bridges
mcw-windows
mcw-windows
Mekanism
Mek Generators
Mek Tools
mightyarchitect
modnametooltip
movingelevators
nuclear_craft
occultism
OptiFine
Patchouli
Placebo
QQP+
Quark
rsgauges
supplementaries
swingthroughgrass
tesseract
theoneprobe
timestages
torchmaster
trashcans
valkyrielib
world+stripper
World Edit CUI
World Edit

I don't fully know what causes it. But when you finish editing a new custom preset, and you boot up minecraft. If you put WriteALL in the world.ini file, it will sometimes insert minecraft:air

I expected to not find blocks of air