SYNC ALTERING QB CUSTOMER INFO
US QuickBooks for Macintosh : 2012
contact sync erased some QB customer info after syncing ... how do I get it back - and - prevent if from happening in the future?
contact sync erased some QB customer info after syncing ... how do I get it back - and - prevent if from happening in the future?

I believe this is a bug, see this community.intuit.com/posts/how-do-i-stop-contact-email-addresses-from-disappearing also be sure to use quickbooks>quickbooks feedback and report your experience.