A user who has just succeeded completing Enterprise Activation after a wipe can't make changes made to the BB's contacts show up in Exchange. Everything else syncs and emails work.

I have switched the device to one-way syncing and bidrectional set to allow the device to win, both times re-sending the IT policy. I tested these with my own BB and it works fine. Which log(s) should I be looking at to help get the bottom of this?

Is there a wireless sync option in address book options on the BlackBerry? That could be a service book issue.

The logs to look in are MAGT and SYNC. SYNC will probably provide more info than the MAGT log but the MAGT log contains a line about almost every issue.

You could try deleting and resending the desktop[SYNC] service book and make sure that the user can see the address book in the list of items to sync during the activation.