[Tex/LaTex] Beamer metropolis theme standout frame formatting of notes

Question

I'm using the metropolis theme for beamer. It has a standout feature for frames. But on those frames, the \note speaker note pages are rendered incorrectly. The text inherits inherit bold face font and centered alignment. Also the date on the speaker notes is wrongly aligned to the center

Another issue arises when used together with the hepnames package to typeset elementary particle names. I set the main font back to Computer Modern (\usefonttheme[onlymath]{serif}), but with hepnames in use, the math font also is typeset in bold face.

I tried to fix it in my \tafelzeit command by resetting the font, but it does not work for the math font if I use hepnames.

Is this a bug in metropolis or am I doing something wrong?

Minimal working example

\documentclass{beamer}

\usepackage{pgfpages}
\setbeameroption{show notes}
\setbeameroption{show notes on second screen=right}

\usetheme{metropolis}
\usefonttheme[onlymath]{serif}

\usepackage{hepnames}


\newcommand{\tafelzeit}[1]{%
    \frame[standout]{%
        \emph{Tafelzeit}
        \note{\raggedright\normalfont #1}
    }
}
\newcommand{\themath}{
    Decay width
    \[ \varGamma\big(\APKzero \rightarrow \Ppositron \, \Pmuon\big)  = a + b = 0 \]
}

\title{Metropolis Standout}
\begin{document}
    \section{Decay Width}

    \begin{frame}
        \themath
        \note{\themath}
    \end{frame}

    \begin{frame}[standout]
        \themath
        \note{\themath}
    \end{frame}

    \tafelzeit{%
        \themath
    }
\end{document}

Everything is correct on normal frames; [standout] frames are rendered with bold face and centered alignment; resetting the font does not reset math fonts, when hepnames is used.

Answer 1

A workaround: move the note outside the frame

\documentclass{beamer}

\usepackage{pgfpages}
\setbeameroption{show notes}
\setbeameroption{show notes on second screen=right}

\usetheme{metropolis}
\usefonttheme[onlymath]{serif}

\usepackage{hepnames}

\newcommand{\themath}{
    Decay width
    \[ \varGamma\big(\APKzero \rightarrow \Ppositron \, \Pmuon\big)  = a + b = 0 \]
}

\title{Metropolis Standout}
\begin{document}

    \begin{frame}
        \themath
        \note{\themath}
    \end{frame}

    \begin{frame}[standout]
        \themath
    \end{frame}
    \note{\themath}

\end{document}