Good morning! This report by Github user SverreStausland has been lingering on the Luaotfload tracker for a while: There appears to be a difference between how certain faces of the Libertine family handle the placement of diacritics. With Version 5.1.2 of the family [0], the "RZI" version (fullname: “Linux Libertine O Semibold Italic”) shows a different behavior than its “RZ” companion (“Linux Libertine O Semibold”). Short demonstration in Context: \definefontfeature [ourfeats] [default] [mode=node] \starttext \start \definedfont [file:LinLibertine_RI.otf*ourfeats] V\char"0306 \stop \start \definedfont [file:LinLibertine_RZI.otf*ourfeats] V\char"0306 \stop \stoptext Note the misaligned combining breve above the latter. An equivalent test for Plain [1] shows that the correct position information is there somewhere in the font, since the Xetex engine typesets it correctly. Best regards, Philipp [0] MD5 hashes of the files: 4bfd3481c1486f5d1ea13304981df7a6 LinLibertine_RZI.otf 153765bd2b29d6026fb2fa0b198a4995 LinLibertine_RZ.otf [1] https://bitbucket.org/phg/lua-la-tex-tests/src/tip/pln-diacritics-1.tex