How do I add a fax label for a 365 Contact?

I added a new contact to Outlook, it showed up in RingCentral right away.  I added a FAX number to the Outlook contact, it is not syncing the change.  I hit the sync button several times before and after exiting RingCentral App, but still the fax number does not appear.  I tried to add it to the RingCentral / 365 phone book, but only have the choices as WORK (already used, will allow adding a second WORK number.  Home and Mobile are also options, Fax is not.  Trying to send a fax from the contact icon pulls the main WORK number.