Didn't have this issue until recently, one of the latest updates mustve caused it. Crimson Thickets just dont have any trees at all, just some grass and flower patches. Using a BOP worldtype but that wasn't an issue for me before.

only thing ive done is disabled palm trees in the config, not sure if that might have bunked it up

Uploading a fix to CurseForge, thanks for letting me know!