Any value other than 0 in the "Muscles & Settings" tab of Humanoid Rig results with IK ignoring these settings.

For example, i can set my shoulders to have 0 degree of movement in all axis and it will lock it fine. But if i change this limit to 0.2, then it just breaks off from this limit and act like theres no such limit when i move my arms.

This issue affects other joints under "Per-Muscle Settings" as well.