Hello!
I’m animating a ledge climb-up animation in Maya and I’m using HumanIK. I’m able to create the poses but I’m having an issue with the hands.
I have pinned my character’s hands to the edge of the ledge for the first 16 frames or so, but the rest of the body moves. My problem is that the hands will still move in the frames in between. For example, they might do a circle only to end up back where they where.
Any animators know how to avoid this?
I use 3D Max but the logic is the same.
The IK lock has to consist from one keyframe to the next. I assume HumanIK is similar to biped/CAT where it has duel IK/FK switching on both arms and legs.
So the tween between IK keys are assuming FK motion/control when they should be staying in the IK logic. if two keys (one key on frame 0 and one key on frame 10) are both set to IK lock - the tween should keep the limb in place. If a FK key is created between those two IK keys - say on frame 5 the hand will be locked on frame, float up as a curved based FK key through frame 5 and return to be locked to the same position at frame 10.
Maybe there are some stray keyframes between the two IK keys?
Or - I’m sure google has some simple IK limb locking instructions. 
In case this isn’t obvious IK = inverse kinematic, FK = forward kinematic.
It’s hard to answer without knowing exactly what it is you’re doing. Are you actually switching from FK to IK or are you animating it all in IK? If it’s all in IK make sure your animation curves are not overshooting, sounds like it could be that depending on the type of default tangent you have it set to.