Layer blending issues with animations from Mixamo

I´ve been developing a pet project of mine for some time and have run into some issues with the animations.

I downloaded some basic assets from Mixamo to replace the current "programming art" and as an attempt to educate myself on the Mecanim system and how to blend animations.

However, after some time tinkering, I´ve run into something of a wall...

Animations are essentially a collection of keyframes that apply localized rotations/translations to 'bones'.
And layer blending is merely the...

Layer blending issues with animations from Mixamo