'mathml,mathjax' not compiling complex indices without curly brackets

[yalguzaq]

$\LaTeX$ allows writing complex indices like $x_\mathbb{R}$ ($x_\mathbb{R}$) without curly brackets as the code is unambiguous. When I compile such expressions using make4ht file.tex everything works fine. As soon as I turn on mathml,mathjax mode: make4ht file.tex 'mathml,mathjax' make4ht breaks down.

Note: file tex is a minimal file containing $x_\mathbb{R}$.

[michal-h21]

This is one issue that it not easily fixable, unfortunately. See this page for more details. It contains a Lua script that tries to pre-process the file, and to add the brackets before passing to make4ht.

[yalguzaq]

Understood, thanks!