Grand Ball: Guests not showing up in their formal outfits

According to the grand ball event UI, if I don't choose a dress code guests would attend the ball in their own formalwear attire that was assigned to them in CAS. Instead what happens is guests will show up in a randomly generated formal outfit that is not what I assigned. Every single guest. And they wear the same randomly generated monstrosity at the next ball as well so there is something in the game that remembers these outfits. I do not want to choose a dresscode as I want sims to show up in THEIR outfits which I assigned to them, especially since the dresscodes aren't that much better and none are suitable for a a ball.

Is there a way to fix this aside from asking every guest individually to change into their formalwear? It's the biggest thing that is ruining my ball events for me, and makes me not want to host them, yet I have to every other day for the noble career.