Previously I was able to PRINT TO FAX
In the printer dialogue, there used to be an option to enter a Fax number. It seems to have disappeard, Not sure when, cause I dont fax often.
Mac 10.14.6 Mojave
WorkCentre 6505DN LAN Fax v1.8
Few Screen Shots of the Printer Dialog Box and Setting Box
In the last screenshot, change Safari to Xerox Features and you will be able to change the Job Type from Normal to Fax
Change Job Type to FAX, don't go into Fax settings. I can't supply screenshots as I don't have a Mac to do it on.