PDF text search doesn't find first word in section title

Question

When I run lualatex on the following MWE, open the resulting PDF in either Evince or Okular, and search for foo, I get zero matches. If I instead search for f oo (note the space between the f and oo) then a match is found. Searching for bar works fine. If I select "Foo" in the PDF, copy it, and paste it into a plain text document, I get F oo (note the space).

\documentclass[twoside]{article} % Works if twoside is removed.
\usepackage[tracking=true]{microtype} % Works if commented out or tracking=true removed.
\usepackage{geometry} % Works if commented out.
\usepackage{titlesec}
\titleformat{\section}{\normalfont\scshape}{}{0pt}{} % Works if commented out or \scshape removed.
\titlespacing*{\section}{ % Works if commented out.
  -1110630sp % Works if -1110629sp or greater.
}{*1.5}{*2}
\begin{document}%
\section{Foo Bar}%
\end{document}

If I tweak the above MWE as described in the comments, then searching for foo works (as does copy+paste).

Can anyone explain what is going wrong?

Answer 1

Your example work fine for me on windows both in the sumatra viewer and the adobe viewer.

But as @Sveinung wrote in a comment: pdf viewer have to guess if a space is a real space or not and if the font is tracked they can err quite easily.

You would have to tag the pdf (see e.g. https://tex.stackexchange.com/a/444308/2388) and use real space char to reduce such problems (but it probably wouldn't prevent them completly).

You could also try the accsupp package to add Foo as /ActualText.

Answer 2

That bug was recently fixed in Poppler, so it will eventually get to Evince.