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. 

*Chuckling* Such an easy fix to a very complex and hindering problem, you deserve accolades, "It WORKS!!"  I am curious though how long have you had this problem? this thing had been a serious thorn

*Chuckling* Such an easy fix to a very complex and hindering problem, you deserve accolades, "It WORKS!!"  I am curious though how long have you had this problem? this thing had been a serious thorn

This was my first time really getting back to the animation side of development. I believe this is an IClone 8 thing as I know this didnt happen in IC7. But man did i waste about 3 days fixing this the wrong way...

At least you figured it out, if by any chance you know the "Holy Grail" for changing inplace motion to root motion, toss a bone my way, please

Same snipps. Just go to FK select the root, set akey at 0
Move to the end of the animation then move the bone forward to the general forward direction. 
Make sure in the curve editor you set this to linear (for walk / run/ sprint) so you dont get weird animation loops. The check to animation so it doesnt look like the feet are slipping. Then Save it out as Movement_RM 
I have also did this for RM Jumping and sprint jumping. so you dont have to do weird root motion hacks I've seen going around. 

20% of original size (was 2559x1439) - Click to enlarge