Like when the character is having sex or using a toy , at that time the upper part looks almost frozen , like there is no effect reaching the breasts
Viewing post in My Jazzy Lolly Crush (MyJLC) [v1.8] comments
Well, if you use a vibrator on the ass, the breasts won't vibrate normally. But if you use a vibro-wand directly on the breast, the effect will be noticeable.
The animation of breasts depends on many factors: size, firmness, clothing (tightness), toys used, and the force of push during sex. For example, larger breasts have more complex physics.