First time replying to a question! I had a similar issue- enabling root motion would rotate the animation 90 degrees backwards on the X axis. After a lot of frustration, I eventually traced the problem to the skeleton in Maya, where I discovered that, when parent-constrained to the root control, the root bone had a 90 degree rotation on the X axis, for some weird reason. Because of that, it was importing with a 90 degree rotation on the root, and so it’d rotate 90 degrees whenever root motion was enabled. Once I fixed the rig in Maya (and reimported the anims), root motion worked properly. Ik its been awhile since ya made this post, and Idk what software u made the rig in, but lmk if this helps!