Sims 4 Game Error; Ambrosia

Hi, I am having trouble with my Sims 4 game. I have a ghost Sim that I would like to not be ghostly anymore. I learned that if you level a Sims up in cooking, gardening, and fishing, that you could have the Sim you level up make ambrosia to bring the ghost Sim back to life. So I leveled up another Sim in those categories, and gathered everything needed to make ambrosia. Which takes a lot of reward points to get the youth potion required to make the ambrosia. I have befriended the ghost/added her to my household, and made the her eat ambrosia many times, to no avail. I have tried having her eat It sitting down, standing up, having the Sim who made the ambrosia gift it to the ghost Sim and then having her eat it, the game goes through the motions, the whole magical transformation bit, but afterward when she returns to the ground she is still a ghost. The ghost Sim was originally a vampire Sim who died do to exposure to the sun. Not really sure what to do now, but it has been frustrating to spend so much time preparing the other Sim to be able to make ambrosia for nothing. Is there something I can do? Something I am not doing right?