It's okay! Thank you for the input! (I know you also have a game of your own to develop! ^^)
So that's is normal by design, she will wear the night / day clothing set once she took a shower (for example: take a shower at night, day -> night set, take a shower at day, night -> day) so, she will keep wearing the night / day clothing before she take a shower
so in that screenshot, if that time you haven't take a shower with her, she will keep wearing the clothing until you take a shower alone or with her~ and the towel is like a transition to change her clothing set!
Unless... you already take a shower and she doesn't change her set despite the towel or doesn't even change to towel at all, then it is a bug!