lualatex doesn't find FiraMath-Regular.otf

[Uwe Siart]

After today's update (reinstall of firamath after yesterday's removal)
lualatex doesn't find FiraMath-Regular.otf anymore, but xelatex does.

The following MWE works perfectly fine with xelatex. But with lualatex I
get

! Package fontspec Error: The font "FiraMath-Regular" cannot be found.

\documentclass{scrartcl}
\usepackage{unicode-math}
\setmathfont{FiraMath-Regular.otf}
\begin{document}
Test $a = b$.
\end{document}

I did mktexlsr and fc-cache -f but neither helped.

The font file definitely exists and kpsewhich also finds it.

-- 
Uwe