Hello,
there is a bug in QXP's handlung of contextual ligatures in Open Type fonts. Although in the (italic) font I am using the feature clig (contextual ligatures) is ON, QXP does not show these ligatures. All other ligature features work fine. The corresponding glyphs are, of course, present in the font and they show up correctly in Adobe Indesign.
I did not find any bug report page within the QXP website. Hoping Quark is interested in reports.