Combining diacritical mark is misaligned with luatex, but not with xetex [closed]

Consider the following code:

\documentclass{article}
\usepackage{fontspec}
\setmainfont[BoldItalicFont = {* Semibold Italic}]{Linux Libertine O}
\begin{document}
\textit{\textbf{V\char"0306}}
\end{document}


Why does this give the correct output with XeLaTeX, but not with LuaLaTeX?

XeLaTeX:

LuLaTeX:

(This question is a spin-off from Why choose LuaLaTeX over XeLaTeX?)

• Really seems like a bug somewhere. – egreg Jun 13 '14 at 19:16
• The output is perfect with Brill, CharisSIL, DejaVu, Heuristica, and Source Sans Pro, all of which have the mark and mkmk features. Junicode has these features but fails the test. Amiri has the mark but not the mkmk feature, and also fails this test. I haven’t found a font without these features which produces the desired output in luatex. – Thérèse Jun 13 '14 at 21:16
• The mkmk should not have any rule here since there are no mark to mark interaction involved. depending on how the font is built, you might not also need the mark feature to get correct output. – Khaled Hosny Jun 16 '14 at 11:15
• I also tried combining chinese, persian and russian in one document. I wasn't for anything, tried it just for fun, so when it didn't work, I just quit. But LuaLaTeX produced only whitespace instead of chinese, while XeLaTeX produced empty boxes. I guess better support and bug fixes will be present in future. Maybe, better version of LuaTeX will be in TeX Live 17. – Michael Fraiman Jun 3 '17 at 21:46
• closed as unclear what you're asking What? It's obvious! LuaTeX does it wrong while XeTeX is doing it correctly. What is the reason for that difference. There is no possibility how a question can be more clear that this one. – radlan Nov 2 '19 at 14:02

\documentclass{article}