Just a reflect behaviour that needs adjusting in Rhino 8.
A sub D model with reflect applied on one axis.
Extract a selection of surfaces of Sub D model.
Extracted sub d surfaces show as maintaining symmetry but they do not. Any adjustments made are no longer reflected.
You have to remove reflect and add again to start working with symmetry again. I think it should either should lose symmetry after you extract the surface or, more effective would be to keep the symmetry and work.