Font/Text help files don't seem to show how Open Type features work in XDP. I've searched the help files to no avail.
It's possible I'm using incorrect terminology, but there seems to be no mention of how the fi button works.

I'm using a font that is new to me (Changing W00) which works fine in Illustrator CC 2017 but not in the latest update of XDP.
I can use it in XDP by using Windows Character Map, but I thought we has moved on from the Stone Age now.