May it be, that there is the following bug in Quark XPress 8 (Windows)?:
If an OT feature contains the language statement "language DEU;", Quark XPress ignores all the following features. The feature itself (the one, that contains the language statement "language DEU;") works.
In this case the font was built with FontLab and did contain one languagesystem statement only, namely "languagesystem latn dflt;". (More to the point, that’s the default statement of FontLab, isn’t it?)
And I think, there is another bug:
If a feature file contains the statement "languagesystem DFLT dflt;" only (font built with MakeOTF [AFDKO]), but not the statement "languagesystem latn dflt;", none of the features work, at least not in German.
Oh, maybe another bug:
Quark XPress seems to dislike substituting spaces in features. Example: While "sub space x space by x;" would not work, "sub slash x slash by x;" works as intended.
Can anyone verify one or more of these bugs?