so the result (when playing online) is not a short acceleration but a slow slice..? If it's a short acceleration, then it's not the same issue.
I've not tested it yet online, I think that doing it intentionally will result in a no shot slice most times. But I also think there's a few ms range where the shot is still recognized as short accel, because of the lag, so it will be a short accel with the animation of slice (my problem). This is coherent with the fact that it happens mostly when I'm gonna use the short accel as an approach shot, because when you do an approach shot you usually release the button as soon as possible, to start running forward.
But, still it's happening since the last update, so I don't know if you introduced the combo "b1+b2+up released at the last moment=no shot slice" just in the last update, or instead you increased the ms range where the shot is still recognized as a short accel, despite having the slice animation. I'm sure that previously it wasn't happening, or at least it was happening very rarely. And keep in mind that in the .dmo the animation is still short accel, not slice one, so the input is recognized as short accel, while the engine that manages online matches recognizes a slice animation (maybe because of the lag).