Hi, not sure if you still struggle with that, but maybe that could be a hint.
I worked on something similar a year ago, so I don’t remember much, but I think I fixed it by manually setting my character’s location in Tick function of my cpp file.
So, something like Char->SetActorLocation(/*vector in-between left and right foot positions*/)
My control rig’s ‘Full Body IK’ node had root behaviour set to ‘Pin to Input’, I suggest checking that too.