Problem with sffamily

with this code, the \pi and \alpha disappear when \sffamily is active.

\documentclass{article}
\usepackage[warnings-off={mathtools-colon,mathtools-overbracket},math-style=french]{unicode-math}
\usepackage[default]{fontsetup}
\usepackage{siunitx}
\sisetup{%
   text-family-to-math = true,%
   text-series-to-math = true,%
}%
\begin{document}

2$\pi$ -- 3$\alpha$ --
\SI[parse-numbers=false]{2\pi}{\centi\meter} --
\SI[parse-numbers=false]{3\alpha}{\centi\meter}

{\bfseries
2$\pi$ -- 3$\alpha$ --
\SI[parse-numbers=false]{2\pi}{\centi\meter} --
\SI[parse-numbers=false]{3\alpha}{\centi\meter}
}

{\sffamily
2$\pi$ -- 3$\alpha$ --
\SI[parse-numbers=false]{2\pi}{\centi\meter} --
\SI[parse-numbers=false]{3\alpha}{\centi\meter}
}

{\sffamily\bfseries
2$\pi$ -- 3$\alpha$ --
\SI[parse-numbers=false]{2\pi}{\centi\meter} --
\SI[parse-numbers=false]{3\alpha}{\centi\meter}
}
\end{document}

Start by compiling the minimal LaTeX document in the report with unicode-math, fontsetup, and siunitx, then compare the normal, bold, sans-serif, and bold sans-serif cases. Trace the siunitx handling of text-family-to-math and text-series-to-math for the failing cases. Done means that \pi and \alpha render in all four contexts, including both \SI examples.