If you are using the motions from default free resource motion pack, most of them are in-place motion, it means that they have no forward movement.
It is because those motions are designed for display use in Character Creator 4. Otherwise the character in CC4 will walk away from the viewport.
See the screenshot below.
For now, there is no function for converting in-place motion into root motion automatically in iC8 & CC4.
Please try to walk the character with Motion Director:
https://courses.reallusion.com/home/iclone/motion-director?v=iclone-8-tutorial-getting-started-with-motion-director
https://courses.reallusion.com/home/iclone/motion-director
Or download the free motions from Actorcore:
https://actorcore.reallusion.com/3d-motion/free?saleType=All
By the way, root motion can convert into in-place motion by one click.