It is not just the extra parts. Feet are standard parts but do not swap.

Load LH: set to no IK; zero; bend Left Foot -20 degrees and Left Shoulder down 45 degrees; , then Figure>pose Symmetry > Swap Left and Right.

Arm pose is swapped as should. Feet pose is not swapped.

Same behavior for other figures (V4 Ang2). ==> Conclude not specific to LH but generic.