I have a similar groom binding issue with a character while using a root motion animation in 4.25
Character groom works fine when it animates in place in a cycle, but as soon as the character offsets from origin via the imported animation (root motion) the quality of the groom deteriorates and becomes stepped / jagged like the image bellow.
A work around I found was to animate the character in place externally in Maya, then in UE I animate the transforms for the character.