The second ‘non-rendering’ figure is badly formed.
View in Monochrome.
If possible reverse backwards faces [which render ‘transparent’ otherwise].
You might need to reapply the backs’ materials onto the fronts.
If it were me, then rather than slog through this, I’d tend to [re]use the successful figure component.
Make it unique, edit it, mirror its geometry, perhaps rotate it about the Z axis a little, delete/add/scale parts as needed so it looks different enough in the view…
Even recolor some of the surfaces with new cloned materials, so the viewer is fooled into seeing two separate people…