I don't know that it's a bug, exactly. It is annoying, though. All you need to do is change your sim into their career outfit (you can do this by clicking on a dresser, or as a self-interaction), then have them go to a mirror and select "change appearance". From there you can change their hairstyle and make up. You can click the padlock icon so that the hairstyle is used for all their outfits, or so that it only affects the outfit they're wearing at the time - in this case, their career outfit. To add shoes to their outfit, have them use the dresser to "plan outfit". You can't change their default career outfit, but you can add a second (and third) outfit, and can style them however you like. The outfit they are wearing when you exit CAS is the one that will be set for that outfit. Hope that makes sense.