Font/Text help files don't seem to show how Open Type features work in XDP

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.

If you insert the Text Tool cursor in some text and press the F1 key, a context sensitive menu opens. If you scroll down a bit you see the explanation.

If you key in Help > Index > Ligatures it provides a better description. But OT Ligatures produces nothing.

There are 126 discretionary ligatures that work just fine in XDP in the version you can purchase from a place like MyFonts.

Attachment 116990

Thank you Gary and Mike for responding.
I don't imagine that the problem I'm having is solely related to XDP, as I don't get any open type features with this font in Affinity Designer or CorelDraw X6 either.
But I do get the expected result in Illustrator CC 2017, which, if I didn't, I would think the problem was in the font.

But in regard to my original question about the XDP help files, they only mention the fi button by showing where it is on the toolbar, but not how one accesses the features.
We are flying blind without some kind of visual reference like the one I've shown of part of Illustrator's Glyph Panel. The orange version in my screenshot was imported from Illustrator, by the way
Bob.

I agree that the help is scanty. I agree that there needs to be a glyphs panel. I also think that if a feature is not present, the menu selections themselves need disabled else it will cause confusion.

The version of the font you downloaded from the site you did (I know from where that version came from) has the code related to discretionary ligatures removed. So while the glyphs are still present, there is no means of turning them on inside the font.

I have the legal version of that font and my screen shot was produced using XDP with merely turning on discretionary ligatures on the text.