Sequoia's won't generate?

[ShadowFile]

I can't get a sequoia to generate in my world, I've just spent the past few hours doing everything I could think of. I flew around with the default settings and configs, I raised and lowered the spawn rarity to multiple values, and I've turned off all biomes except for plains and flown around for a good 30 minutes with no success. I am currently waiting with a 7x7 grid of saplings to see if it will grow. Any help would be much appreciated.