为什么我看不到第二部分的标题？

Question

我更新了 MikTex 的软件包，突然发现字体有问题：
我正在使用LyX 在 WIN10 X64。

梅威瑟：

 % Preview source code

%% LyX 2.3.6 created this file.  For more info, see http://www.lyx.org/.
%% Do not edit unless you really know what you are doing.
\documentclass[a4paper,english,hebrew,numbers=noenddot]{scrartcl}

\usepackage{fontspec}

\makeatletter

%%%%%%%%%%%%%%%%%%%%%%%%%%%%%% User specified LaTeX commands.
\newfontfamily\hebrewfont[Script=Hebrew]{FreeSans}
\newfontfamily\hebrewfonttt[Script=Hebrew]{FreeSans}
\newfontfamily\hebrewfontsf[Script=Hebrew]{FreeSans}


\makeatother

\usepackage{polyglossia}
\setdefaultlanguage{hebrew}
\setotherlanguage{english}
\begin{document}

\section{שלום}

שלום 
\begin{english}[variant=american]%
abcd
\end{english}%

\section{אבגד}
\end{document}

输出如下：

第二部分的标题אבגד- 缺失....

现在，如果我删除英文文本：

  % Preview source code

%% LyX 2.3.6 created this file.  For more info, see http://www.lyx.org/.
%% Do not edit unless you really know what you are doing.
\documentclass[a4paper,english,hebrew,numbers=noenddot]{scrartcl}

\usepackage{fontspec}

\makeatletter

%%%%%%%%%%%%%%%%%%%%%%%%%%%%%% User specified LaTeX commands.
\newfontfamily\hebrewfont[Script=Hebrew]{FreeSans}
\newfontfamily\hebrewfonttt[Script=Hebrew]{FreeSans}
\newfontfamily\hebrewfontsf[Script=Hebrew]{FreeSans}


\makeatother

\usepackage{polyglossia}
\setdefaultlanguage{hebrew}
\setotherlanguage{english}
\begin{document}

\section{שלום}

שלום 

\section{אבגד}
\end{document}

输出很好：

你知道为什么会发生这种情况吗？我该如何解决？

谢谢你！