I can't use custom skin tones on occult sims

The skins haven't been updated for years and the problem didn't start until a good amount of time after the last update. I also tried reinstalling my game and repairing my game and that did nothing. My current occult sims that had custom skin still have it by the way. For some reason, the options for custom skin just don't appear for occult sims. For example: I can use my custom skin on a mermaid's human form but I don't get the option for their mermaid form and I can use custom skins for aliens both in alien and human form. I'm really confused and frustrated by this.