Given the following code:

\enableregime [utf]
\mainlanguage [en]
\definepapersize[sheet][width=1280px, height=960px]
\setuppapersize[sheet][sheet]
\setupexternalfigures[directory={img, 
    /home/ubuntu/EGU2016-Presentation, 
    /home/ubuntu/ConTeXt/img}]
\usemodule[simplefonts]
\setmainfont[Adventor][expansion=quality,protrusion=quality]
\setupcolors[state=start]
\definecolor[faimsblue][h=1B3E93]
\definecolor[faimsorange][h=F68E1E]
\setuphead[section][placehead=yes, page=yes, number=no, align=middle, style={\setupbodyfont[40pt]}]

\setuplayout[
    backspace=.01\pagewidth,
    header=0pt,
    footer=.02\pageheight,
    topspace=.185\pageheight,
    cutspace-.1\pagewidth,
    width=.87\pagewidth,
    height=.798\pageheight,
    bottomspace=.8cm,
    bottom=12pt   
    ]
\setuppagenumbering[location=]
\setupinteraction
  [page=yes,
   color=faimsblue,
   contrastcolor=faimsorange,
   menu=on,
   state=start]
\setupsubpagenumber
  [way=bytext,
   state=start]
\startinteractionmenu[bottom]
{\interactionbar[alternative=f,width=\makeupwidth,height=2ex]}
\stopinteractionmenu
\starttext
\input knuth
\section{section 1}
\input knuth

\section{section 2}
\input knuth


\section{section 3}
\input knuth


\section{section 4}
\input knuth
\stoptext

(used in a real presentation: http://context.fedarch.org/Context/presentation.pdf with environment at https://github.com/FAIMS/EGU2016-Presentation/blob/master/envpresentation.tex)

it seems that the interactionmenu doesn't have a button for the final page. I'm assuming I did something wrong, but I'm not quite sure what it is.