[XeTeX] fontsize option 12pt in koma-script makes \left(\right) produce wrong lengths with unicode-math

[Tobias Schoel]

Hi,

I think the title says it all: Adding the option 12pt to the scrartcl 
class (koma script) makes \left(\right) don't work properly in display 
math mode.

Minimal example:

\documentclass[12pt]{scrartcl}

\usepackage{fontspec}
\usepackage{unicode-math}

\setmainfont[Ligatures=TeX]{TeX Gyre Pagella}
\setmathfont[Scale=MatchUppercase]{Asana Math}

\begin{document}

\[\left(\left(\frac{1}{2}\right)^2\right)\]

\end{document}

Without the 12pt option it works correctly.

Why is that and how to help?

bye

Toscho