reference:
http://tex.stackexchange.com/questions/197243/tex4ht-removes-spaces-in-array-column-when-including-a-package-even-if-the-packa

In the following cases, Tex4ht generates an HTML file with no spaces between the columns of the matrix if some package is included, even if the package is not used.

Removing the package, the space between the columns shows up again.

This only affects tex4ht and not pdflatex. This happens when array is used inside tabular or longtable. Outside of these, then this problem do not show up.

-----------------
\documentclass[12pt,notitlepage]{article}%
\usepackage{tabularx} %commenting this off restores the spaces
\begin{document}

\begin{tabular}{p{6in}}
\[
\left[ \begin {array}{cc}
0 & 1 \\
-25 & -4
\end {array}
\right]
\]
\end{tabular}
\end{document}
------------------------------

htlatex foo.tex

Then the HTML file shows the spaces are lost.

The following packages also cause the same problem, but this is due to them loading the array package internally: siunitx, ltxtable and any other package that loads the array package will show the above problem.

These problems do not show up with the Latex code is outside the tabular environment. As I said in the comment below, this is a small example from large document. I use tabular with 2 columns to help me array the layout of the document. Left side is the command and the right side is the output. Both can be latex code as shown above.