I've had this happen a handful of times and I'm wondering what I can do about it. For reference using Freesurfer 5.0.0.
Edited a brain and ran "recon-all -autorecon2 -autorecon3 -s subj_id" which completed without error. The resulting brain had chunks of missing auxiliary volume in areas that I had not touched at all. This is bizarre and I am not sure what to do about it. Images of said issue attached of both main and auxiliary volumes.