This is a huge annoyance, I recently added a ghost horse to a household I made for The Sims 4 Life And Death EP and when I dropped them on a residential lot the horse was alive and not a ghost so I w...
Ideas
It was a ghost on the gallery ? Possibly that's causing issues, depending on how it made into a ghost horse in the first place.
If you a living horse to your household and let that die of old age. Do you have the same issues ?