Set HOME in Citroen WipNav RNEG

I've just bought a second-hand C8 with WipNav. I see that when you select destination to navigate to, there is an option "HOME", but it's greyed out (The WipNav seems to have had a factory reset). I can't find any information on how to set the HOME address; it's not in the manual that came with the car, nor can I work it out. Attempting to save a location with that name just created an address book entry "Home", but this is different, and needs you to go to the address book to select it.

What have I missed? Thanks!