I would like to have the same font and especially the same size for inmargin texts. Why is the following program not honouring the size setting?

% Font in margin text
\def\MarkMaster{\inmargin[location=left]{{\switchtobodyfont[sans,8pt]\red MASTER SECTION}}}
\starttext
\startchapter[title=\MarkMaster test title]
\input tufte
\MarkMaster
\input tufte
\blank
contextversion=\contextversion
\stopchapter
\stoptext

Hans van der Meer