hyperref pointing to the wrong equation using subequations

Question

I'm using the following code to write an article, but I'm having some problems cross-referencing the equations with hyperref.

The \eqref{} code returns the right equation's number. But the hyperlinks of the first and second \eqref{} point to equations (1) and (2), and not to correct equations (3a) and (3b), inside the \begin{subequations} ambient. Last \eqref{} instead works correctly. What is wrong with this code?

Thank you for the help.

\documentclass[a4paper,10pt]{article}
\usepackage[a-1b]{pdfx}
\hypersetup{hidelinks}
\usepackage{type1ec}
\usepackage[T1]{fontenc}
\usepackage[utf8]{inputenc}
\usepackage{amsmath}
\usepackage{amssymb}
\usepackage{mathtools}

\begin{document}

\begin{equation}
A=B
\end{equation}
\begin{equation}
B=C
\end{equation}
\begin{subequations}
\begin{equation}
C=D
\label{eq:1}
\end{equation}
\begin{equation}
D=E
\label{eq:2}
\end{equation}
\end{subequations}
\begin{equation}
E=F
\label{eq:3}
\end{equation}

\eqref{eq:1} \eqref{eq:2} \eqref{eq:3}

\end{document}

Answer 1

i'm not familiar with pdfx, but it presumably takes the place of hyperref.

it is, with very few exceptions, necessary for hyperref to be called last.

you have pdfx first.