Blendspace + walking back

I’m trying to create a character that can move with animations from Mixamo. I got animations for going forward, strafing left and right, and I created an animation that goes back (going forward at speed -1). So I’ve got my blendspace like this :

Which is basically what they tell you to do in the character animation tutorial. Now if you watch the video :

You can see that it doesn’t work. Going forward is ok, but going backwards is inverted… why ?