Just tested same thing IN the editor, and it seems this is not runtime related, because if I scale root bone in the editor it has same effect. That is weird. So it has to do with the way animation is rigged. But I have no idea what's wrong. Should I still put it in tracker?
It's like as if "constraint scale" is not being affected by the root bone scale.
UPD: Also, when we try to change constraint scale now manually in the editor (the new version) it just freezes. (when the root bone is scaled. It is reproducable every time)
UPD2: So I did some digging, and made a video to show exactly what's going on, as you can see animation works just fine, but when root bone is scaled, it somehow makes all bones clamp up in single spots, reason being, scale of each bone is affected in such a way, that it's 0. When I click on a bone that is affected, it shows as 0 scale for X, and you can see that at some point it swaps to become "1" without me typing it, I just clicked. And then it goes back to 0 if clicked again. Due to this problem you can see how animation looks all wrong. because most of it is scaled into single 0 scale points. And all I did was to scale root bone to 0.3
Here is the video:
