I wrote a small Opentype feature script based on the advanced contextual alternates. In Glyphs it works perfectly fine and as expected. Whenever I try to use it in inDesign however things break apart.
It is not a font caching issue, I made sure multiple times.
This is the feature code. Basically just contextual alternates with some substitutions after the alternates have been done:
sub @LongLetters by knurdlemidlong;
sub @ShortLetters by knurdlemidshort;
sub @MediumLetters by knurdlemid;
lookup ISOLATED1 {
ignore sub @MiddleKnurdles' @AllKnurdles;
ignore sub @AllLetters @MiddleKnurdles';
sub @MiddleKnurdles' by @SoloKnurdles;
} ISOLATED1;
lookup INITIAL1 {
ignore sub @AllKnurdles @MiddleKnurdles';
sub @MiddleKnurdles' by @LeftKnurdles;
} INITIAL1;
lookup FINAL1 {
ignore sub @MiddleKnurdles' @AllKnurdles;
sub @MiddleKnurdles' by @RightKnurdles;
} FINAL1;
sub @RightKnurdles' hairspace by @MiddleKnurdles;
sub hairspace @LeftKnurdles' by @MiddleKnurdles;
sub @AllKnurdles hairspace' by knurdleleft_syllable knurdleright_syllable;
sub knurdleright_syllable @LeftKnurdles' by @MiddleKnurdles;
sub knurdleright_syllable @SoloKnurdles' by @MiddleKnurdles;
Edit: I tested in in Drawbot as well and it does work fine there. So it really does seem to be an InDesign problem.