Yeah, I can see where it would indeed get functionally complex to orchestrate the application of the saved pose (and indeed how multiple poses might be saved).

Not just multiple instances of say V4, but say, you might have a V4 an M4, Miki4, etc... that you were saving poses for... and expecting to load back in.

It would be a bit trickier when it comes to loading than say the hand pose, with its pop up left or right hand question, there.

No wonder it doesn't work / isn't available.

The "Select Subset" box is obviously just intended to facilitate saving data for a subset of parts of the one figure.

;)