It sure as heck sounds like a bug in Illustrator.

I'll flag this thread to some of our friends at Adobe and perhaps it can be looked into, and if it is an Illustrator bug it might get fixed in some future release.

Regards,

T

Thanks Thomas.

Thanks for bringing this problem to our attention. I have confirmed the incorrect functioning and submitted a bug.

This is funny, I've experienced it before and thought that it was just the way it is. I noticed that a workaround is to kern the ending letter pair beforehand and it would reflect once the ligature was activated, if that makes sense. It will be nice to have a fix for this.

IMHO, Illustrator is indeed so have not "friendly" with otf feature, LoL. But the problem also would be recheck to the "kerning classes" groups definition. I Just remembering you. Think, In this case, kerning for "k" and "f" should be separate to be two session:
"k" ----> "k_left" and "k_right". Same way for
"f" ----> "f_left" and "f_right".

And then:
"ffk" should be completely grouping with "k_left" and "f_right", and
"ff" should be completely grouping with "f_left" and "f_right"

I hope this correct.
Nice to introducing you.
Best regards.

@andiawmasry: I don't think you understand the bug report. You can't do *manual* kerning in Illustrator between the ligature and a following glyph. It's nothing to do with whether the font's built-in kerning was properly constructed. (Though it would be interesting to see if Illustrator also fails to correctly use the built-in kerning between a ligature and a following glyph.)

Cheers,

T

@Thomas ... you're right ... I've already mixed up FL and Illustrator :-)
Thanks

Best regards

This issue no longer happens in Illustrator CS6 - looks like it has been fixed.

Cheers,
RK