Hey all,
This is by design, since only Humans and Ghosts can become fairies. Half-aliens can become other occults, but not fairies.
Had this same issue as well, no mods. Did some testing and found it only affected my half-alien sim (had trait_OccultAlienPart). When I removed the trait, I was able to plant the fairy seedling.
Cheat console: traits.remove_trait trait_OccultAlienPart
Any occult won't have the option as you can't have two occult states at the same time.
Actually, I've had half alien sims become vampires, werewolves, mermaids, and spellcasters before without issue. Why can half aliens not be fairies specifically? Seems like it might be a bug.
Maybe there was a conflict ?
There's some other issue with Aliens and fairies being reported or maybe they just disallowed it for all occults and aliens is a bug.
I don't know at this point.
Adjusting the title for this a bit.
