Local Polygon Subdivision Not Working With Symmetry

Hi.  I tried out a quick test today to punch a hole through a cube with symmetry turned on and found that it broke symmetry in the process.  To recreate this test, create a cube and enable X-Axis symmetry.  Select a polygon face on the x-axis and inset it... since symmetry is enabled, this should work on both sides.  I would like 8 vertices to make my circle instead of 4 (using the "circularise" operation, followed by "bridge"), so select the inset quad polygon and perform a subdivide operation from the polygon tools menu, with the option "selection only" enabled... notice that it only subdivides the selected polygon on one side of axis of symmetry, and therefore symmetry is broken.  Next undo the operation, then specifically select the inset polygon on BOTH sides of the axis of symmetry.  Once again, perform the subdivide operation with "selection only" enabled.  The polygon has now been subdivided on both sides of the axis of symmetry, yet symmetry has still been broken.  Arguably, one could reintroduce symmetry using the command "symmetry remove-postive/negative and weld", but I don't see why that should be necessary?