If you were talking about the Random Portrait setting, then that won't change the body image until the next version of Strive or if you use the current bugfix patch (neither are yet compatible with this mod). Otherwise if you meant the Random Portrait button added to the slave tab by the Improved Random Portraits mod... then well... that could be a bit complicated since that mod already does that. Chances are that your portraits and bodies folder paths don't match. Not sure where the difference is, but if you selected only one path, then you may have been effected by a bug introduced by my bugfix patch while expanding the options for selecting paths.