AlegreyaSans, microtype's tracking feature and footnotes

Question

My question is closely related to this one.

I'm using pdfLaTeX and microtype with AlegreyaSans as my sans serif font. I managed to adjust the answer given by Ulrike Fischer in the above question in so far, as the small caps are spaced out nicely in both the roman and the sans font in body text. In footnotes, however, tracking only works for the serif font. I've boiled the problem down to this MWE:

\documentclass{article}

\usepackage[osf]{AlegreyaSans}

\usepackage[tracking=true]{microtype}
\DeclareMicrotypeSet*[tracking]{mysmallcaps}{
    encoding = *,
    family = {rm*},
    shape = {sc*, scit},
    font = */AlegreyaSansSC-OsF/*/*/*
    }
\SetTracking{
    encoding = *,
    shape = {sc*, scit},
    family = {rm*},
    font = */AlegreyaSansSC-OsF/*/*/*
    }{500}

\begin{document}
Some \textsc{small caps} in roman.\footnote{Some \textsc{small caps} inside a footnote in roman.}

{\sffamily Some \textsc{small caps} in sans.}\footnote{\sffamily Some \textsc{small caps} inside a footnote in sans.}
\end{document}

Everything is fine in normal body text:

But footnotes break the tracking of the sans serif font:

What is happening here?

Answer 1

Setting up font sets in microtype can be quite hard work. The most important thing that one must understand is that the asterix is not a wildcard, but that is is replaced by a specific value (the default). So the last asterix in the font option e.g. restricts the tracking to normalsize.

As you want to set tracking to the normal shape of "alegeyra smallcaps" family and to the scshape from the main font I can find only this:

\documentclass{article}
\usepackage[T1]{fontenc}
\usepackage[osf]{AlegreyaSans}

\usepackage[tracking=true,letterspace=500]{microtype}

\DeclareMicrotypeSet*[tracking]{mysmallcaps}
  {
    family={cmr},
    shape=sc*,
    font={
          */\AlegreyaSansSCfamily/*/*/*,
          */\AlegreyaSansSCfamily/*/*/footnotesize,
          */\AlegreyaSansSCfamily/*/*/large
          }
  }



\begin{document}
Some \textsc{small caps} in sans. 
\footnotesize  Some \textsc{small caps} in footnotesize.

{\sffamily Some \textsc{small caps} in sans. 
\footnotesize  Some \textsc{small caps} in footnotesize.
\large \textsc{large}}

\end{document}