[NEEDS INPUT] [IL] Mermaids use normal swim style on high Fitness

It usually happens in my mermaid family on the naturalistic island of Mua...something.  It seemed completely random to me, I could be playing for hours without reloading things because my sims lived on that island, and every once in a while they'd enter the water and start the wrong swim cycle.  Resetting the sims don't help, but going in and out of the water fixes it.