Bad mathchar (79119) using htlatex+mathml with \uparrow with align from amsmath package

Bad mathchar (79119) using htlatex+mathml with \uparrow with align from amsmath package

texlive 2012 debian package:
\documentclass[]{article}%
\usepackage{amsmath}  
\begin{document} 
\begin{align}
      &    \uparrow\sum F
\end{align}
\end{document}
compile with
htlatex report.tex "htm,mathml" " -cunihtf"
gives
/usr/share/texmf/tex/generic/tex4ht/html-mml.4ht)
(/usr/share/texmf/tex/generic/tex4ht/html4-uni.4ht))
(./report.aux)
! Bad mathchar (79119). <argument>  & \uparrow \sum F
                               l.8 \end{align}
                ?
But when compile as
 htlatex report.tex "htm,xhtml" " -cunihtf"
or
 htlatex report.tex "htm" " -cunihtf"
No error.
What should I do? Is this a bug in htlatex? any workaround? The problem happens when using \uparrow with mathml and when using align. Without align there is no error.
\documentclass[]{article}%
\usepackage{amsmath}  
\begin{document} 
    $\uparrow\sum F$
\end{document}
Now
  htlatex report.tex "htm,mathml" " -cunihtf"
No error.
update
fyi, if you are using htlatex with mathml watch out for align. Workaround I found for now is to use eqnarray. Now the errors went away. I am trying to compile to HTML code generated by Scientific word, which generated the align Latex code. So I had to edit the code and change all the align to eqnarray as temporary fix for now to get HTML generated.