No superscript or subscript greek letters with EB Garamond and mathspec

Question

When using the EB Garamond font (v. 0.016) with XeLaTeX and mathspec, superscript and subscript greek letters in math mode do not appear in the pdf, though it compiles without error.

\documentclass{article}

\usepackage{mathspec}
\setmainfont{EB Garamond}
\setmathfont(Digits,Latin,Greek){EB Garamond}

\begin{document}
Test
$\alpha^\alpha \beta_\beta$

\end{document}

The problem does not occur when using another font like Crimson.

\documentclass{article}

\usepackage{mathspec}
\setmainfont{EB Garamond}
\setmathfont(Digits,Latin,Greek){Crimson}

\begin{document}
Test
$\alpha^\alpha \beta_\beta$

\end{document}