Can't see if anyone else has asked this but i'll store this here. 
In the current version I guess the root motion applies rotation information in the root as well as other axis movement and in UE4/5 this causes issues with the root motion. (For me at least). Thus far I have had hid to use root to hip then remove the forward hip movement and reanimate just the Y movements by hand.

(Fix) This morning I just realized you can sampled the optimized animation for the animations in question cut the root Y movement. Transfer the root to hip which get rid of the odd XYZ rotation in the root then paste back in the Y movement to the root. Then its ready for resaving the animation back out for exporting to unreal. 

This seems to be an issue on all the animations I have stored from IClone 7 before moving to IClone 8.

Wish I saw this earlier but the more you know... If this was obvious I apologize but if it helps those that do not see this I hope it helps.