Mark (or anyone), I was wondering if there is something amiss...
I can't seem to get symmetry to work in the Hair modelling room, it works fine in 6pro and never had a problem there.
in 7pro I see the green divider activated, I use Cut or Brush or select grow regions, all the tools I've been using so far (all with symmetry button enabled) are not working on both sides.

I has this symmetry problem happen in 6pro using soft select (while vert modeling) which was rectified by exiting 6pro and restarting the application, but doing this in 7pro ends up not resolving it.

In the meanwhile I'll go do my hair in 6pro until someone has an answer...

Ok, I tried to get into 6pro, lol, I notice that the displacement mappings are truly very different.
I ended up going with an older save before the hair was placed on my subject.

I carefully checked symmetry made sure I hit "Center Symmetry Plane" under the HAIR menu dropdown. That might have been the problem when I started my hair on my last attempt.
I started my grow regions form there on with no problem so far.... :)