'File As' in Contacts is not behaving correctly

[Jeff]

Outlook 2007.
I prefer to File As by surname, ie 'Doe, John' - and I sort by this field in
my list of Contacts, so that they are listed with this field leftmost, and I
can see Surnames as I scan down the list. Each of my Contacts is set this
way.
But - and this happened recently - suddenly all of my Contacts in theFile As
field are displaying as 'John Doe'. Open the Contact, and the File As is
definitely set to Doe, John.
I can correct it (one at a time!) by opening the contact, changing File As
to John Doe, save, then change it back to Doe John, save and close - and
then it displays correctly. But since I have hundreds of Contacts I don't
fancy doing this one contact at a time...
Any ideas why the File As convention is being ignored, and how to correct
it?

Here's a hunch I have: I recently got a new Android phone, and I sync my
Contacts via Exchange with the new phone. Could this have screwed things up
somehow? I hold this hunch because:
a) the phone is new and so is this problem;
b) I have another Contacts folder of more obscure contacts, which does not
sync with the phone, and those display in Outlook as Doe, John.

Thanks for being here,
Jeff