If you want to create clips for a HumanIK character and edit the animation in a non-linear fashion using the Trax Editor, note the following:
Ideally, all of the character's IK and FK objects are parented to the same reference object, and you can add this reference object to the character set.
Whether or not you have animated the IK Blend properties becomes important when blending clips for the HumanIK character. When specifying an offset object for the blend, note the following:
If your HumanIK rig has static IK Blend values (no blending between IK and FK solving), set either the Hips FK object or the Control rig reference object as the offset object. If you use the Hips FK node, ensure that all of the rig’s IK objects have IK Blend T and IK Blend R set to 0.
If your HumanIK rig has animated IK Blend values, the Trax Editor cannot evaluate the clips properly unless you use the Control rig reference as the offset object. In some cases, however, even using the Control rig reference does not allow Trax to evaluate the blended clips properly. If you experience issues with this workflow, use the following workaround: