Hi,

If I've understood your problem correctly, simply using ("" "fontspec" nil) in org-latex-packages-alist should fix your issue.

Per the documentation, this third argument stops the package from being used when compiling preview fragments.

Regards,

Sébastien

This is where my fix starts to come in. When org mode does the small

export of the latex fragment it would include the contents of
org-latex-packages-alist in the LaTex headers. Some packages (namely
'fontspec,' used for xelatex) would lead to a failure to create the
dvi file when the .tex file was compiled with the necessary
'latex' command.

To alleviate this problem I designed this wrapper function which
sets org-latex-packages-alist to nil just before executing the
org-latex-preview function.