I'm pretty sure you hit the nail on the head with this one. If contacts are set to save 'On my iPhone' by default, they won't sync with O365. Also go to Settings > Contacts and make sure default account is set to the O365 account. Or maybe there's an iTunes backup you can restore. If the contacts were set to sync back to Outlook and the contacts were deleted from the phone.and contacts sync'd after being e where I'm headed? The contacts are probably gone but check to see if they were saved in iCloud.
