Plugin-created MetaHumans (UE 5.8) have different rest pose than web-created MetaHumans, causing weaker RBF corrective deformation

Development Asset Creation
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Summary

MetaHuman characters created with the in-Engine MetaHuman Character
Creator plugin (UE 5.8) export with a visibly different default
rest/T-pose compared to MetaHumans created via the legacy MetaHuman
Creator web application. This appears to affect RBF corrective
deformation quality — specifically hand/tendon definition — even
though RigLogic and the Post Process Anim BP are confirmed running
correctly on both characters.

Setup

  • Unreal Engine 5.8
  • MetaHuman Character Creator plugin (in-Engine)
  • Comparison character: MetaHuman originally created in the legacy
    web-based MetaHuman Creator (pre-5.6)

Observation

The default rest pose differs between the two: plugin-created
characters have hands rotated slightly outward with straighter
fingers, compared to the web-created character’s rest pose.

When an identical posed animation (hand gripping/flexing) is applied
to both:

  • The web-created character shows clear, anatomically accurate
    tendon/knuckle deformation.
  • The plugin-created character shows visibly softer, rounder
    deformation in the same pose.

I’ve ruled out a few likely causes:

  • Not a texture issue — swapped Cavity/Normal maps between the
    two characters; the deformation difference persisted.
  • Not a disabled RigLogic issue — Post Process ABP is confirmed
    active and running on both characters (screenshots attached).
  • Not solely a body-size/proportion issue — difference persists
    across multiple heights and body compositions.

My current hypothesis is that RBF correctives fire based on the
delta between a joint’s current rotation and its rest-pose
rotation. If the plugin’s default rest pose already sits closer to
a “relaxed” hand position, the same final pose produces a smaller
rotation delta than on the web-creator’s rest pose — resulting in a
proportionally weaker corrective blend for the same visual pose.

Question for Epic / community

  • Is this a known/intended difference between the two creation
    paths, or a regression?
  • Is there a supported way to align the plugin-generated rest pose
    with the legacy web-creator rest pose without hand-editing the DNA
    file in a DCC tool?

Screenshots attached showing both hands in the same pose, with
Post Process ABP confirmed active on the plugin-created character.

MetaHuman Creator Plugin Hand UE5.8

MetaHuman Creator Online Hand

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Reproduced this independently in Blender using the Character DNA addon (Poly Hammer) — after applying the plugin-exported DNA and posing the fingers into a claw/grip via the control rig, tendon definition remained flat regardless of pose extremity. This confirms the corrective weakness is baked into the DNA file itself at export time, not caused by anything in Unreal’s Post Process ABP, skeleton binding, or the in-Engine viewport — RigLogic evaluation directly against the raw DNA file shows the same result.