Sounds like you have tried everything already, so it would be a hardware escalation: 1-800-821-2797 or 1-800-835-6100
I just tried it, but I still don't have the Fax option on the available Job Types.
I tried both v3 and v4 drivers.
I would first try uninstalling and reinstalling the printer with the Xerox Print Driver.
How can I send a fax from PC?
The job type "Fax" does not show on the Xerox print window for this printer.
Also, windows fax does not recognize B235 as a fax machine.