I do have to add sometimes glyphs in existing fonts. These OTFs do have a lot of ligatures.
After opening and duplicating the font in Glyphs the ligatures are listed in Feature as »dlig«. After exporting the font they won’t work.
Then I changed the ligatures to .liga, all listed okay in Feature. A new export and it won’t work too.
You are testing the font with Font Explorer? I guess you have built up a font cache problem. Delete all instances of the installed font, then delete caches, and restart your machine. And then, use the Adobe folder to avoid caching issues.
Strange is that Glyphs says that it has exported the file (to ID/fonts file), but it’s not there. Export to library/fonts file works, then I do have to copy it into ID/fonts file…
Well, the ligatures do work in Glyphs.
Are you exporting into the right folder?
/Library/Application Support/Adobe/Fonts/
Be careful, there are other Library folders around. It is not ~/Library, and not /System/Library/. And the folder must be called Fonts, do not reuse FontsRequired or whatever other folders happen to start with “Fonts” inside the Adobe App Support folder.
And don’t export into Library/Fonts. You only ever place fonts there when they are completely finished, no sooner. Otherwise, you will run into font cache problems again.
Did you restart your Mac after cache cleaning?
Are you testing in InDesign using the Fonts folder?
Did you make sure you renamed the font family name so there is no conflict?
Did you regenerate the features in Font Info before exporting?
Did you activate ligature substitutions in the target set-up?
The ligature substitutions are in the dlig feature but you only activated the liga feature. So you need to activate OpenType > Discretionary Ligatures or copy the substitutions from the dlig feature into the liga feature.
Note: In German, discretionary ligatures are ‘Bedingte Ligaturen’. As Georg said, you will find them in the OpenType submenu.
If you want automatic feature generation, add a ‘.liga’ suffix to the glyph names. Select all ligatures, press Cmd-Shift-F (=search and replace in glyph names), leave the ‘Find:’ field blank, and put ‘.liga’ into the ‘Replace:’ field. Then refresh features in File > Font Info > Features.