I had the broken sync as well but only when syncing directly to m.google.com, never again with Nuevasync. It was fixed anyway after PR1.2.
I could reproduce it very easily: merge an MSN contact with a Google contact and then sync. Sync fails, not even a resync got it back working. Respectively, when the resync sometimes worked, it broke up merged contacts but not fully. It somehow left traces of the previous merge, so I could not ever remerge MSN and Google contacts again, it gave back some error à la Details alredy exist merge failed or so...