`New TX Math` Package not compatible with `underbrace`

Question

I am trying to use an underbrace option with Garamond Expert with NewTX Math and for some reason the pdf is not generated for the following code as there seem to be some compatibility issues even though no errors are shown.

\documentclass{article}

\usepackage[T1]{fontenc}
\usepackage{garamondx}
\usepackage[garamondx,cmbraces]{newtxmath}


\begin{document}

\[
    S_{classical}[q] = \int\displaylimits_{t_{1}}^{t_{2}} ds\ 
    \underbrace{\left( \frac{m}{3} \frac{t}{2}  \right)  }
\]

\end{document}

On the other hand if I remove the \frac{t}{2} or \frac{m}{3} then the code compiles. Basically, if I use multiple terms inside the \left( and \right) environment then the pdf is not generated even though the code compiles with no errors or warnings.

Another point to note is that if I remove the line \usepackage[garamondx,cmbraces]{newtxmath} then everything works fine but the font I want to use is not the same.

Please suggest me what to do. I have looked at the documentation for the NewTX Math package but couldn't find anything.

Edit 1 :

It seems that it is absolutely not possible to use \left[ and \right] with the NewTX Math package anywhere in the document.

Also, I can't use \underbrace{\left( \frac{m}{3} hi \right)} if the \left( and \right) are inside \underbrace but if they are outside then it is fine.

Edit 2 :

It seems that wherever the pdf is not generated there is a file named missfont.log which is generated with the following entry mktexpk --mfmode / --bdpi 600 --mag 1+0/600 --dpi 600 txex-bar. So I ran apt-file search txex-bar which told me to expect this file with two extensions : tfm and pfb, then I ran a kpsewhich on both and sure enough both are present whereas myfilename.log shows that !pdfTeX error: pdflatex (file txex-bar): Font txex-bar at 600 not found ==> Fatal error occurred, no output PDF file produced!

Edit 3 :

Forcing latexmk to compile results in the following :

kpathsea: Running mktexpk --mfmode / --bdpi 600 --mag 1+0/600 --dpi 600 txex-bar
mktexpk: don't know how to create bitmap font for txex-bar.
mktexpk: perhaps txex-bar is missing from the map file.
kpathsea: Appending font creation commands to missfont.log.
 )
!pdfTeX error: pdflatex (file txex-bar): Font txex-bar at 600 not found
 ==> Fatal error occurred, no output PDF file produced!
Failure to make 'a.pdf'
Latexmk: Errors, in force_mode: so I tried finishing targets
Collected error summary (may duplicate other messages):
  pdflatex: Command for 'pdflatex' gave return code 256

Answer 1

On my TeX Live 2020 system, I was able to compile your MWE by installing the getnonfreefonts script and running the getnonfreefonts.pl script it installed with --sys --refreshmap --all. This correctly installed the map files for the Type 1 version of GaramondX.

If you can use luatex or xetex, I would recommend unicode-math with the Garamond Math font instead.

Here was the output from a very slightly-modified version (I changed the word in the subscript to the operator font.)

Answer 2

I managed to make it work and in case anyone stumbles upon the exact same problem I am providing some information here.

The problem is actually with the the TeXLive 2015 distribution where the NewTX Math has a few problems with execution. If one upgrades to TeXLive 2020 things work out.