\micro in package siunitx stopped working

Question

Using the \micro command in siunitx worked fine some months ago. But suddenly, maybe caused by software updates, some fellows and me aren't able to use \micro in siunitx.

There is no error, the \mu is simply not displayed in the generated PDF-file.

We are currently using dirty workarounds such as using 10^{-6} or \upgreek instead, but we are very interested in solving the problem.

We are using LuaLatex as Latex-engine on different systems (macOs and different Ubuntu distros).

Thanks in advance!

Edit: I am using LuaLatex Version 1.0.4 (TeX Live 2017); my minimal code example, causing the error, which was working fine some months ago, is the following:

\documentclass{scrartcl}
\usepackage{polyglossia}
\setmainlanguage{german}
\usepackage{unicode-math}
\usepackage{siunitx}
\begin{document}\si{\micro}\end{document}

Answer 1

From this answer, just add a \sisetup:

\documentclass{scrartcl}
\usepackage{polyglossia}
\setmainlanguage{german}
\usepackage{unicode-math}
\usepackage{siunitx}
\sisetup{math-micro=\text{µ},text-micro=µ}
\begin{document}\si{\micro}\end{document}