QuarkAgency
commented
3 months ago I put here additional screens. Here the source rig doesn't contains any root bone but the root motion is embedded in the armature itself :
Issue is when I retarget, this root motion information is transfered to the first bone in hierarchy (spine in my case) but it would better to create a channel for the armature and insert the root motion here. (at least optionnaly)
In some skeleton like UE5, the root is not defined as a bone this is the armature itself.
The root motion should be transferred it isn ot the case between armature transform.