Hi
Poser uses what we call "Hard" Ik Chains
( yeah Ironic I know).
Meaning the Ik chain lengths are based on a completely Zeroed Figure position.
This is very limiting frankly

For example If I load a figure that has IK on for the legs as a default. and do NOT move him, Especially the hip
translations,
then Immediately load up walk designer
and create a simple walk cycle , he walks
fine with no "Knee snaps".

However if I load my figure and turn off IK for the legs and move him /her around THEN activate IK
for the legs I get Major Jitter problems for the feet& legs.
Many Figure Creators& Non animators Think they are doing you a favor by Having Figures that have no Ik or load with IK OFF as the Default. but such nonsense is a detriment to Character animation

I had major problems with "dorks" Feet when creating
the Stair Climbing tutorial until I Zeroed him using the
joint editor tool."Resetting" his IK chains.

You results may Vary dependent upon the figure you are using
but try Zeroing out the figure using the Joint Editor tool.
before Doing any IK related tasks.

Hope this helps

Cheers.

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