Comment (by Roland Haas):

Some more background information: Wikipedia has a list of browsers supporting MathML https://en.wikipedia.org/wiki/MathML) Chrome did support MathML at one point but phased it out https://www.cnet.com/news/google-subtracts-mathml-from-chrome-and-anger-multiplies/

Our server is that generates the HTML pages (from the release branch) is indeed too old to produce mathjax files. It can however produce files that render all equations as images.

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Ticket URL: https://bitbucket.org/einsteintoolkit/tickets/issues/2442/latex-rendering-issue-in-local-reduce