I created a contextual substitution to substitute an alternative form of the letter d following the letter f, l or t. The code I used is shown below. It compiles without errors.
sub [f l t] d’ by d.alt;
This works when I test it in the text editing window. See the sub_glyphs.png screenshot. However, the substitution doesn’t work in InDesign. See the screenshot sub_indesign.png.
I am exporting the font to Library > Application Support > Adobe > Fonts. I shut down and restarted Creative Cloud after exporting the font.
I think the feature has to be called ‘calt’.
