UE5 Fullbody IK shows bizarre behavior

When following the example from the wiki I was able to setup the Full Body IK node for the mannequin without any problems. Currently, I am testing the Full Body Ik feature with a custom model that I am still working on but I am encountering some very strange behaviour when I am trying out the Full Body IK node with my own model.

For starters, the root bone is showing up as a red bone.

Another model with almost the same skeleton, however, does not show up with a red root bone.

Second, when creating a control gizmo the gizmo itself is absurdly huge.
I can scale the gizmo of course but I don’t understand why it is not appropriately sized.

Lastly and the main issue:
When setting the root bone of the Fullbody IK node to the root and add set an effector bone the whole mesh warps into whatever that is.

I have no idea if these issues are specific to the Fullbody IK or not but I have not encountered these issues before.

I have the same problem with mesh deformation. All my models that I exported from blender behave the same way. Unreal Mannequin works fine.

I wish I could share a solution with you but I too am still experiencing this problem.

Hello! Take a look at blender export settings on this video (specially the part concerning armature scale and primary/secondary bone) to solve the scale issue with the gizmos.

Assuming you’re using blender to make your characters :smiley:

As for the red bone, I bet it’s because your root bone isn’t at world origin (0,0,0).

Thanks and good luck!

Why replaced Full body IK in Unreal Engine 5?
The old one was perfect in UE4, I’m really disappointed.
Something that works well should not be changed.
I sincerely hope that he will abandon the works and return to the old version of full body IK.
But please don’t make the old version deprecated.
Sorry for my English.

About Full Body IK, I’m happy to say that everything is back to normal and much better in UE5 preview 2 Well done unreal engine team.