Thanks for the link, but sadly this issue is still happening for me in 5.0.2. I don’t think the bug you linked is the same thing we’re seeing here. That bug says root motion isn’t being retargeted at all - in my experience, root motion is being retargeted correctly, but the hip/pelvis bone isn’t being retargeted correctly relative to the root bone.
So far I’ve tried rebuilding the IK rig and retargeter assets, and messing around with some of the options in both of them, with no luck.
Since several of us are seeing this, I’m just going to submit a bug report and see what Epic says. Hopefully they’ll either confirm it’s a bug or just tell us what we’re doing wrong. I’ll write back if/when I hear anything.