{align*} breaks the parser
I used some MathML to LaTeX converters to supply annotations for all MathML formulas on MDN. I also tested some outputs with TeXZilla and noticed that formulas using {align*} weren't properly parsed. Once replaced with \begin{aligned}, it worked fine.
Errored:
\begin{align*}
x + 3y + 4z &= 2 \\
3y - 4z &= 5 \\
z &= 4
\end{align*}
Worked:
\begin{aligned}
x + 3y + 4z &= 2 \\
3y - 4z &= 5 \\
z &= 4
\end{aligned}
Not sure what’s the difference (the rendering seems identical), but other parsers support the {align*} notation. For example, Temml.
Apparently this is to control automatic numbering of formulas: https://tex.stackexchange.com/questions/9514/whats-the-difference-between-align-and-align
TeXZilla follows https://golem.ph.utexas.edu/~distler/blog/itex2MMLcommands.html and so does not support the starred versions.