If I zoom out using a gesture on Mac trackpad, I get zoom factors like 0.9 (that's ok), but after some time I suddenly get one negative (e.g. -10) and then start to get factors like 1.1. If I apply it to the object's scale, the object is smaller and smaller, when it's virtually invisible it is flipped both horizontally and vertically and then enlarged back in the upside-down position. I'd expect to get the numbers between 0 and 1 all the time.