Hi,
there was a problem on TeX SE [1] where page numbers disappear for a whole chapter when \page[none] is used to hide the numbers on empty left pages in a double sided document.
As can be seen in the following example the page numbers and background on the last two pages disappear when “missing” mode is enabled. This happens when the “blank” option for \page is used without a change in the page number (we are already at page 3 when \page[yes,blank,right] is expanded).
%%%% begin example
\setupbackgrounds[page][background=color,backgroundcolor=gray]
%\enablemode[missing]
\starttext
\dorecurse{6}{\input knuth\par}
% End the current page before \page[blank] is called
\doifmode{missing}{\page}
\page[yes,blank,right]
\dorecurse{6}{\input knuth\par}
\stoptext
%%%% end example