为什么 amstools 在这里不起作用？

Question

看看这个文件，当我在 LyX 上编译它时，它显示：

文件如下：

% Preview source code

%% LyX 2.3.0 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]{scrartcl}
\usepackage{amsmath}
\usepackage{amsthm}
\usepackage{fontspec}
\usepackage{fancyhdr}
\pagestyle{fancy}
\setlength{\parindent}{0bp}
\usepackage[unicode=true,pdfusetitle,
 bookmarks=true,bookmarksnumbered=false,bookmarksopen=false,
 breaklinks=false,pdfborder={0 0 1},backref=false,colorlinks=false]
 {hyperref}

\makeatletter

%%%%%%%%%%%%%%%%%%%%%%%%%%%%%% LyX specific LaTeX commands.
\pdfpageheight\paperheight
\pdfpagewidth\paperwidth


%%%%%%%%%%%%%%%%%%%%%%%%%%%%%% Textclass specific LaTeX commands.
\theoremstyle{definition}
\newtheorem{defn}{\protect\definitionname}

%%%%%%%%%%%%%%%%%%%%%%%%%%%%%% User specified LaTeX commands.
\newfontfamily\hebrewfont[Script=Hebrew]{David CLM}
\newfontfamily\hebrewfonttt[Script=Hebrew]{Miriam Mono CLM}
\newfontfamily\hebrewfontsf[Script=Hebrew]{Yehuda CLM}
\AtBeginDocument{
\renewcommand\footnoterule{%
  \kern -3pt
  \hbox to \textwidth{\hfill\vrule height 0.4pt width .4\textwidth}
  \kern 2.6pt
}}
\usepackage{thmtools}
\usepackage{amsmath}

\declaretheoremstyle[
  headfont=\color{blue}\normalfont\bfseries,
  bodyfont=\color{red}\normalfont\itshape,
]{colored}

\declaretheorem[
  style=colored,
  name=Definition,
]{defn}

\makeatother

\usepackage{polyglossia}
\setdefaultlanguage{hebrew}
\setotherlanguage{english}
\addto\captionsenglish{\renewcommand{\definitionname}{Definition}}
\addto\captionshebrew{\renewcommand{\definitionname}{הגדרה}}
\providecommand{\definitionname}{הגדרה}

\begin{document}

\begin{defn}
אבג
\end{defn}

\end{document}

你能解释一下为什么会这样吗？我该如何解决？

谢谢你！