Copy and Paste Mirror Axis works incorrectly for character's legs

Hi everyone. I’ve stumbled into a problem with Copy and Paste Mirror Axis function during the animation of the walk cycle. It works fine with the upper part of the rig but legs are completely messed up.

All .Ls and .Rs are checked, I’ve tried to ReRoll leg bones altogether and separately, searched all forums, tried to set the rig for legs again following Sebastian Lague “Blender Character Animation: Walk Cycle” tutorial step by step. Nothing helps. Have anyone had the same issue?
Many thanks.
My rig

Your locations are the same. zero for both legs. It’s working correctly. You have not moved your IK control bone because of the way you have it parented to a foot roll bone. Look at your transforms. You might want to do some research on IK leg rigging and include a root bone.
You have moved the parent of IK R control to get your pose. The IK control R bone is still in the same relative position because of the parenting.