IMac (Intel) :: FaceTime Sync To IPhone And IPad Air

I setup my new iMac (purchased 14 May 2014) with a whole bunch of FaceTime contacts.   These are there in my FaceTime pane. I bought an iPadAir last week and also have an iPhone. On both these Apple devices I also entered some FaceTime contact data, tried both out and they worked just fine; that is they talked to each other and other people. As this information was slightly different on all three devices, I wanted them to automatically follow what I have on my iMac, so I plugged them both in to the iMac. I then (separately) did a Sync of both devices from iTunes, and all the data for FaceTime in both cases instead of being updated and streamlined/synchronized with my iMac has been wiped. automatically rather than have to enter and re-enter all the data again and again each time I do a Sync. 

Note:  when I did the Sync the music I added today went where it should, so there's no problem with connections, etc. On the Info page I've clicked on "Sync Contacts" which would seem to be what was necessary. Now when I try to Sync either of these devices, the Sync process goes on and on and never stops. I can't see any way of stopping it other than doing a Force Quit of iTunes - which is pretty useless as I will obviously want to Sync these and my other Apple devices again in the future. As a result of this neither of these devices will now Sync with my iMac, other than locking themselves into a cintinuous loop. As I've just bought both the iMac and the iPadAir I could contact Apple direct, but I thought I'd try here first.

Info:
iMac, OS X Mavericks (10.9.2)