I made a couple of models in 1.3 which used the rotation Y for breathing or bounce movements, it seems that they got changed in 1.4 (1.4.1/1.4.2) & these models don't look right now (breath cycle is slower than it used to be, bounce rotation "rotational drag" goes way out of the intended range)
(as an additional note, the "Bounce" on these models was set at 100)