Related bugs currently found are that the game stops when milking in that state, and that only clothes are on top of the body when you put on clothes in that state. The latter requires a new illustration for almost all outfits, but I think the former is a problem that can be solved.
Also, not all outfits have this bug. Some outfits, like sleeveless, don't reflect the mega boob's size, but they are dressed normally.