Previously, I had worked with XeTeXinterchartoks since I wanted to use a different font for uppercase letters. The code worked exactly as I wanted it to when compiling with xelatex.
However, I have recently changed laptops and have reinstalled texlive-full. Now, when I compile the code, I get missing characters and extra spaces in seemingly random places.
What is going on and how can I fix this?
I am attaching a MWE, one that I also used when figuring how to create this code in the first place (Different font for capital/upper case letters)
\documentclass[a4paper,11pt]{book}
\usepackage[default]{frcursive}
\XeTeXinterchartokenstate = 1\relax
\newXeTeXintercharclass\ucletterclass
\ExplSyntaxOn
\int_step_inline:nnnn {"0041}{1}{"005A}
{ \XeTeXcharclass #1 = \ucletterclass }
\ExplSyntaxOff
\XeTeXinterchartoks 0 \ucletterclass = {\begingroup \fontfamily{phv}\fontseries{m}\fontshape{n}\selectfont}
\XeTeXinterchartoks \ucletterclass 0 = {\endgroup}
\XeTeXinterchartoks 4095 \ucletterclass = {\begingroup \fontfamily{phv}\fontseries{m}\fontshape{n}\selectfont}
\XeTeXinterchartoks \ucletterclass 4095= {\endgroup}
\begin{document}
This is some text.
This is some text with an acronym in it GMT
This is some text with a proper name in it: London
\end{document}


