What is the right way to do tracking in LuaLaTeX at the moment?
My problem is basically the same as in the older question Problem with interword spacing in LuaLaTeX.
However, the answer given by egreg does not seem to work anymore.
In particular the output seems to depend on whether I include the % in front of \setmainfont in the following or not (using \setmainfont makes the extra interword spacing disappear, which is not what I want).
\documentclass{article}
\usepackage{microtype}
\usepackage{fontspec}
%\setmainfont{Latin Modern Roman}
\begin{document}
\textls[400]{AB CD EF}
\showoutput
\end{document}
I'm using TeX Live 2017 (from Arch Linux repositories), the version of LuaLaTeX is 1.0.4 and the version of microtype is 2.7.