Deform bones not showing up in UE5 when using Child of Constraint

[Disar]

Describe the bug I understand that constraints need to be baked, but the problem is that all of the bones disappear with the exception of none deform bones and the root when i try to load the glb into unreal. Without the constraint it's perfectly fine

To Reproduce In blender the green bones have child of set to the red bone. Sampling is turned on at export and bake all Objects Animations doesn't make a difference.

Expected behavior All bones should be imported in ue5

Screenshots

.blend file/ .gltf (mandatory) gltfexportbones.zip

Version

• OS: win11
• Blender Version 4.1.1

Additional context This might be an issue with Unreal but so far it only happens when i try to export skeletal meshes/animations that use a constraint ( child of constraint in this case ). IK constraints work perfectly fine however.

[julienduroure]

Hello, Reimporting in Blender shows that all 10 bones are here.

Checking the exported file shows the 10 joints exported:

Can't find any issue here, at first look.

[Disar]

That's weird, then I don't know. UE5 doesn't throw an error either. It only happens with the constraints 🤔 Ill check later if Godot has the same issue.

[julienduroure]

[Disar]

sigh, thanks for checking it out. I guess UE5 is the culprit here, is there anything specific that's different in the file when using/baking with constraints?

[julienduroure]

They can have some difference is bone is a deformation bone or not, but we don't check if bones have constraint or not.

[julienduroure]

More than a month without any answer, closing this ticket. Feel free to comment and provide new information if you want me to have a look