LyX with XeTeX refuses to use the italics version of David CLM

Question

I've been using a setup of LyX with XeTeX on my laptop and it's been working just fine. However, I installed it on my desktop (with the same fonts, packages, everything) and I've noticed that whenever I try to use emphasis (\emph) on Hebrew text it just doesn't work.

The problem seems to be specifically with the font David CLM, which is the default roman font and works fine on my other computer. With any other font set as the default, the problem disappears. I tried reinstalling the font on my desktop, and the italics option works fine in MS Word and other places, but when I try to emphasize text in LyX (and the same with making it slanted and italics via the menu) the output is just normal text.

If it isn't clear from the first paragraph, the LaTeX preamble is the same as the one on my laptop (which does work correctly) but I attached it here just in case:

%%% Set Hebrew and English fonts
\setmonofont[Script=Hebrew]{Miriam Mono CLM}
\newfontfamily{\englishfont}[Ligatures=TeX]{TeX Gyre Pagella}
%\newfontfamily{\englishfont}[Ligatures=TeX]{Latin Modern Roman}
% Proper font size in math mode.
\setmathrm[Ligatures=TeX]{Latin Modern Math}

%%% Another way is to set just the Hebrew fonts:
% \newfontfamily\hebrewfont[Script=Hebrew]{David CLM}
% \newfontfamily\hebrewfonttt[Script=Hebrew]{Miriam Mono CLM}
% \newfontfamily\hebrewfontsf[Script=Hebrew]{Simple CLM}
% consider using \usepackage{iffont}

%%% Sets both header and footer
\fancyhf{} % sets to nothing
\renewcommand{\headrulewidth}{0pt}
\fancyfoot[C]{\textup{\thepage}}

\renewcommand*{\refname}{Bibliography}

%%% Some alternative styles
\ifcsname question\endcsname
  \theoremstyle{definition}
  \newtheorem{quesh}[thm]{שאלה}
  \renewenvironment{question}{\begin{quesh}}{\end{quesh}}
\else
\fi
\ifcsname sol*\endcsname
  \theoremstyle{remark}
  \newtheorem*{emphsol*}{פתרון}
  \renewenvironment{sol*}{\begin{emphsol*}}{\end{emphsol*}}
\else
\fi

\renewcommand{\labelenumi}{(\alph{enumi})}
\renewcommand{\labelenumii}{\arabic{enumii})}

Answer 1

First, check your .log file for warning messages about any fonts not being found.

Next, make sure you’ve downloaded and installed the Culmus fonts, including DavidCLM-MediumItalic.otf. You might want to re-run fc-cache -f -s -v and luaotfload-tool -f -u -p -v to make sure they’re indexed.

Finally, you might load the fonts by filename:

\newfontfamily\hebrewfont{DavidCLM}[
  Script = Hebrew ,
  Ligatures = Discretionary ,
  UprightFont = *-Medium ,
  BoldFont = *-Bold ,
  ItalicFont = *-MediumItalic ,
  BoldItalicFont = *-BoldItalic ,
  Extension = .otf ]

Some installations may use the extension .ttf or have a different filename, so one way around that would be to move these definitions to a file named DavidCLM.fontspec:

\defaultfontfeatures[DavidCLM]{
  Ligatures = Discretionary ,
  UprightFont = *-Medium ,
  BoldFont = *-Bold ,
  ItalicFont = *-MediumItalic ,
  BoldItalicFont = *-BoldItalic ,
  Extension = .otf
}

You could then use \newfontfamily\hebrewfont{DavidCLM}[Script=Hebrew] or \babelfont[hebrew]{rm}[Language=Default]{DavidCLM}. If you ever need to compile on an installation with .ttf filenames, you can then edit only the .fontspec file.