Do the normal ligatures work? The font contains 'normal' ligatures for fb, fh, ff, fj, fi, fk, and (kudos!) fï and fì. The round top of the 'f' should be distinctly different in the ligated characters.
Do other OpenType features work? The font offers Small Caps, Caps to Small Caps, and Superscript work (this last one only for "1", "2" and "3"). If you set the applied language to Dutch, you should see a localized 'tight' form for "ij"; localized to Polish, the acute changes to a kreska (hard to see). In Romanian, the cedilla from S cedilla and T cedilla should change to a subscripted comma.
Unfortunately none of the english ligatures are working, but the small caps, subscript and superscript are all working just fine.
The ij ligature in Dutch works just fine as well.
Thanks for your response!
Okay - thanks anyway for trying. I read the information out of the font and there are no special instructions for English, other than the defaults, which should include both normal and discretionary ligatures. So to me it sounds as if the font data itself is correct.
Just to rule out a former bug: did you install the font into your system the usual way, or did you put it inside a Document Fonts folder? This bug prevented some OpenType features to work from within a Doc Fonts folder, but ought to have been weeded out a few versions ago.
Previously I was using SkyFonts but disabled that and installed the .otf files from github as you would install any font, open the files with Font Book and press install, if I reveal the fonts in finder from within Font Book it takes me to /Users/Andrew/Library/Fonts.
I should probably mention I was also using Suitcase Fusion but uninstalled that if that might help.
Thanks again for your help,
Edit: After all this time it was the tracking that was set to 20... it's been a long day.