Creating Alien Sibling Not Recognised

adamclark83

One of my alien sims got married last night and so that her house would be in good hands when she moved in with her spouse, I created a sibling for her. But when it got in game, it didn't recognise them as related. I went into CAS and noticed the relationship somehow changed itself from "Sisters" to "Roommates". I change it back, but go back into the game and it changed back again on its own.