Possible bug (Twitchy Animations) with Unity 5.3.4f1 & Mixamo characters?!?

I'm having this really strange issue that I was hoping someone could help me with.. I've seen numerous people complaining about a similar issue with animations "twitching", but most of the time they were using different animations and the thought was that perhaps it was an issue with animation keyframes, or exporting the animations, or something along those lines...

My problem is, I'm using the Standard Asset animations with a Mixamo character (Erika Archer w/Bow) and I'm getting some serious twitching going on... Perhaps someone might have an idea on how to fix it?

UPDATE: I have tried other characters now with the same result.

Click here to see the Twitchy Animation Example