Female sims keep jacking off invisible cocks

[roadkillv1]

Not sure if this is the place to ask as I've never really used this site before, but...sometimes my female sims will go off somewhere alone and just start tugging the air, or trying to suck themselves off. I've gone over the settings like 5 times and the game is meant to recognise all the sims by their gender, they're very distinctly set to male/female. Is this some animation bug from one of the extra mods? I've told it to make sure it is checking what their gender is but still, the girls just insist on playing with invisible cocks...