After scanning other Smart Resym threads…
I’ve tried SPivot with Unify and Lowest Subdivisions, but I still get this result?
If you started your model with zspheres you should then take that mesh into a modelling app and delete one half and make a symmetrical mesh. Goz the mesh back into zbrush,l do a divide and check the mesh has no errors and then you should be good to go. zsphere interpenetrate sometimes so they are rarely symmetrical. If your mesh comes from another app check for anomalies and reset xform for max, delete history for maya.