Hi Jack, thanks for the gsap.
From what i see the overwrite auto does not work for tweens initiated via css className.
So if you have say an on-mouseover and add a css class {css:{className:"+=class1"}} and then mouse-out before the css property tweens are complete and remove the class {css:{className:"-=class1"}}, the first tween/s are not cancelled and continue to completion - and then the remove class takes effect immediately.
If you use overwrite "all" - all tweens stop as expected.
Cheers