In the first image below you will see this animation that the root starts at 90 degrees and ends at 0 degrees. In the second picture the pelvis has at the most around a 20 degree offset on the Z axis throughout the animation and in the 3rd picture the animation has all that data baked onto the skeleton itself....not the root....

20% of original size (was 2560x1373) - Click to enlarge
20% of original size (was 2560x1373) - Click to enlarge20% of original size (was 2560x1373) - Click to enlarge

Alright, I've tried just about everything...I don't think there is a way to fix this.

I made a video for you all so that you could see exactly what I was talking about.

https://youtu.be/0n60Ci474QM

I just had the most Epic Case of Dumb Luck in history and found a simple solution....it's so simple that I'm lead to believe this has something to do with the actual reason that Root Motion isn't working on these animations in the first place

20% of original size (was 2560x1373) - Click to enlarge

That's all I did....I was trying to change it from a Quaternion Coordinate system to a Cartesian one so I could read the animation data...I set it to XYZ on the Pelvis and realized by accident that the Pelvis was no longer Rotating...only the Root.....

I just had the most Epic Case of Dumb Luck in history and found a simple solution....it's so simple that I'm lead to believe this has something to do with the actual reason that Root Motion isn't working on these animations in the first place

20% of original size (was 2560x1373) - Click to enlarge

That's all I did....I was trying to change it from a Quaternion Coordinate system to a Cartesian one so I could read the animation data...I set it to XYZ on the Pelvis and realized by accident that the Pelvis was no longer Rotating...only the Root.....When I Exported it from Blender I imported it into Unreal and Forced the Root to lock....Now it's still rotating in the wrong direction but at least the entire body is no longer rotating..I should be able to do this on the root now too...Re-import it into iClone 8 and then add the rotation back to the root and export it....

Ok Well I tried this again with a different animation and come to find out it's the simple act of bringing it into Blender and then Exporting it as a new animation that does this....and all it does is fix the rotation of the root not the position..at least not on the Z axis
When I tried this on a climbing animation, 'Force Root Lock' in the Unreal Engine stopped the Rotation and X, Y movement but he still went up.

So after some investigation this issue only seems to be effecting Unreal Engine Animations...Also I've exported some animations from Unreal Engine 5 where the only way I could get them into CC4 was if I first re-exported them out of Blender, otherwise I would keep getting error's saying they were incompatible....even if I specifically made a rig for that specific character in that specific animation before attempting the import.

Update: So I thought that this wasn't effecting Mixamo animations but it actually does, the animations it effects seems to be random. Sometimes it works sometimes it doesn't but it's predictable in that if it doesn't work for an animation no amount of retargeting will fix it.