Does the substitution occur before or after the ligature features? Or is there another substitution interfering? The order of the features is important. Perhaps t_i is already caught by something else.
You can send the .glyphs file to support at this domain if you would like us to have a look.
After checking with a Th ligature I have (without the alternative), the ligature occurs, then is overwritten by the punctuation following it (on this occasion, the ligature reverts to a Capital T followed by a lower case alternative h without the join).
So if that’s the case then surely “sub t.alt’ i.alt’ @Punctuation by t_i.alt3” should work, as it would revert to these two glyphs?
Thanks for the suggestions, unfortunately neither of them work.
The top suggestion just removes the ligature at the end of the word, making it into a joining ligature.
And the bottom suggestion just makes every letter into an ‘end’ (non joining) letter even when it is followed by another letter (despite me making a new class with all of the lowercase letters) meaning that the ignore function isn’t working for whatever reason. I’ve tried this in both orders, but neither worked.
Is there a term to indicate a line break which I could then add to the @Punctuation class? Like you said, as I had it before it worked for everything except for when you pressed enter without any punctuation or a space…