texmath-0.7: tests/writers/mtable-08.tex
\begin{matrix}
{\phantom{\text{fail}}H\phantom{\text{fail}}} \\
T \\
U \\
\end{matrix} = \begin{matrix}
H \\
T \\
{\phantom{\text{fail}}U\phantom{\text{fail}}} \\
\end{matrix}
\begin{matrix}
{\phantom{\text{fail}}H\phantom{\text{fail}}} \\
T \\
U \\
\end{matrix} = \begin{matrix}
H \\
T \\
{\phantom{\text{fail}}U\phantom{\text{fail}}} \\
\end{matrix}