My sim won't turn into a mermaid?

@KatNip - do you remove caches before starting up your game? Remove caches, then go to the save, remove any occult status, add occult, or try remove occult, try adding a different occult and removing it. I do have Hybrid installed now, but I didn't have Hybrid when I had my first experience with tailess mermaids a few years ago, but adding occult did work.

On occasion on recent older saves some scale legged mermaids do not get a tail while they are swimming. Removing the occult again and adding it back fixes it. I use Hybrid all the time now. I hope your mermaid issue gets fixed.