Module [[math]] uses MathJax to process TeX languaje. The interpreter of MathJax is taken from cdn.mathjax.org, but this is not correct now, as that server was shutting down one year ago, on April 30, 2017.
This is the advise warning when inspecting with the Developer Tools of my browser:
MathJax.js?config=default:32 WARNING: cdn.mathjax.org has been retired. Check https://www.mathjax.org/cdn-shutting-down/ for migration tips.
Here is the list of other CDN services that can be used instead, the recommended one being cdnjs: http://docs.mathjax.org/en/latest/start.html#mathjax-cdn