A root motion controlled character would travel further than they should when both EnableUpdateRateOptimizations is on and a.URO.ForceAnimRate is set above 1.
Changing "Root Motion from Montages Only" to "Root Motion from Everything" seems to correct the character movement distance.
1. Open the attached project
2. PIE to see how both characters travel usually
3. Set a.URO.ForceAnimRate above 1 using console
4. PIE again - root motion controlled character travel much further
There's no existing public thread on this issue, so head over to Questions & Answers just mention UE-39021 in the post.