Probably a credit thing. She wanted one thing. The studio wanted another. So in the end, uncreditedMaybe she was hiding?
Nerds have been waving her name like a flag for the last 40 years saying 'Look! Star trek is sooo progressive, a woman and black!"
It's almost like she new Google was coming and the first 9000 results for her name search request would be about how she was a defense mechanism form white men whenever someone rails that Star Trek is too white and too male.