Error when creating full body IK effectors for animated character
You cannot add full body IK effectors to a character that is already animated with traditional FK, IK, or motion capture data. You can only create FBIK effectors for characters with no previous animation.
See Prepare your character for full body IK, Label or rename your character’s joints, and Create the full body IK system for your character.
See Retargeting workflow .
Characterization fails for characters with HipsTranslation joints
FBIK effectors corrupt skinning of characters with HipsTranslation joints
Constrained FBIK effectors break FBIK solution
If you constrain your FBIK effectors to other objects (for example, control objects), your character’s FBIK IK animation (input skeleton) will not follow its FBIK effectors. This is because during playback, FBIK is only activated for effectors whose Reach values are set to 1.0 (pure IK), and constraining your effectors causes your Reach values to become values other than 1.0.