\setmathfont no longer working in TeXShop in macOS Monterey

Question

I got a new computer that came with Monterey, and I restored everything from a backup of my previous computer, which had Catalina (10.5.7), so every font and every setting should have remained intact.

However, MacTeX no longer changes the math font to whatever is set in the \setmathfont command; it leaves the font intact regardless of that command. It does change the main font to whatever is set in the \setmainfont command, though, which is odd.

I've checked that the font is installed (it is). My MacTeX version is 2015 (!).

I'm using the mathspec package and compiling in XeLaTeX.

Edit: Here's a MWE:

\documentclass[11pt]{article}
\usepackage{amsmath}
\usepackage{amssymb}
\usepackage{latexsym}
\usepackage{graphics}
\usepackage{epstopdf}
\usepackage{amsfonts}
\usepackage{mathspec}
\setmainfont[Ligatures={Common,TeX},Numbers={OldStyle,Proportional}]{Calluna}
\setsansfont[Ligatures={Common,TeX},Numbers={Lining,Proportional}]{Calluna}
\setmathfont(Digits,Latin,Greek)[Arabic=Regular,Uppercase=Plain,Lowercase=Plain,Numbers={Lining,Monospaced}]{Calluna}
\newcommand*{\eq}[1]{\begin{eqnarray}#1\end{eqnarray}}
\begin{document}\sloppy
\eq{E & = & \frac{E_0}{\sqrt{\rho}},e^{\pm i\left(k\rho-\omega t\right)}\nonumber}
\vfill
\end{document}