IEEETran can't produce italic et al

Question

I am trying to submit a paper to IEEE, I noticed that example papers have Italy et al. at their reference section. However, i just can't get it to work.

I will really appreciate if someone can shine some light on this subject.

MWE below:

\documentclass[lettersize,journal]{IEEEtran}
\usepackage{amsmath,amsfonts}
\usepackage{algorithmic}
\usepackage{algorithm}
\usepackage{array}
\usepackage[caption=false,font=normalsize,labelfont=sf,textfont=sf]{subfig}
\usepackage{textcomp}
\usepackage{stfloats}
\usepackage{url}
\usepackage{verbatim}
\usepackage{graphicx}
% \usepackage{placeins}
\usepackage{cite}
\usepackage[numbers]{natbib}
\hyphenation{op-tical net-works semi-conduc-tor IEEE-Xplore}
\usepackage{cleveref}
\begin{document}
\title{Test}
\author{Test}
% The paper headers
\markboth{Test}%
{Test}
% \IEEEpubid{0000--0000/00$00.00~\copyright~2021 IEEE}
% Remember, if you use this you must call \IEEEpubidadjcol in the second
% column for its text to clear the IEEEpubid mark.
\maketitle
\begin{abstract}
    Test
\end{abstract}
\begin{IEEEkeywords}
Test
\end{IEEEkeywords}
\nocite{*}
\bibliographystyle{IEEEtran}
\bibliography{references}
\end{document}

references.bib

@article{tieleman2012lecture,
  title   = {Lecture 6.5-rmsprop: Divide the gradient by a running average of its recent magnitude},
  author  = {Tieleman, Tijmen and Hinton, Geoffrey and others},
  journal = {COURSERA: Neural networks for machine learning},
  volume  = {4},
  number  = {2},
  pages   = {26--31},
  year    = {2012}
}

Distribution installed with texlive2023-20230313.iso Xelatex

---

After further investigation, I found that \emph or \textit have no effect. Since I am using XeLatex, adding \usepackage{fontspec} sloved this issue.

Reference: \emph{} no longer works as expected in XeLaTeX / LuaLaTeX

But i still don't understand the cause.