Restatable Does not Show Theorem Number

Question

I learned about restatable from this answer. However, when I put the theorem in the appendix, its reference does not have a number. Here is a MWE:

\documentclass{amsart}
\usepackage{thmtools} 
\usepackage{thm-restate}
\newtheorem{theorem}{Theorem}[section]
\usepackage{hyperref}
\begin{document}
\begin{restatable}{theorem}{thm}
  Everybody knows that $1 + 1 = 2$.
\end{restatable}
I would like this \ref{thm} to display A.1.
\appendix
\section{Proofs}
\thm\label{thm}
\begin{proof}
  Proof is trivial.
\end{proof}
\end{document}

Answer 1

Move the \label{thm} into restatable* environment:

\documentclass{amsart}
\usepackage{thmtools} 
\usepackage{thm-restate}
\newtheorem{theorem}{Theorem}[section]
\usepackage{hyperref}
\begin{document}
\begin{restatable}{theorem}{thm}\label{thm} % <<< \label moved to here
  Everybody knows that $1 + 1 = 2$.
\end{restatable}
I would like this \ref{thm} to display A.1.
\appendix
\section{Proofs}
\thm
\begin{proof}
  Proof is trivial.
\end{proof}
\end{document}