My code is here, The table here contains many footnote, but it does not appear at the bottom of page. Please help me to resolve this issue.
\documentclass[journal]{IEEEtran}
\usepackage{graphicx}
\usepackage{subfig}
\usepackage{caption}
\usepackage{lipsum}
\usepackage{tablefootnote}
\usepackage{hyperref}
\usepackage{amsmath, amssymb}
\usepackage{csquotes}
\usepackage[demo,
export]{adjustbox}
\usepackage{stfloats}
\usepackage{makecell,
ltablex} % new
\usepackage{makecell, tabularx} % changed
\renewcommand\theadfont{\small\bfseries} % new
\renewcommand\theadgape{} % new
\setcellgapes{3pt} % new
\usepackage{siunitx}
\usepackage{enumitem}
\usepackage{etoolbox} %
\AtBeginEnvironment{tabularx}{%
\setlist[itemize]{nosep,
leftmargin=*,
label=\textbullet,
before=\begin{minipage}[t]{\linewidth}, % <---
after=\end{minipage} % <---
} }
\newcommand{\specialcell}[2][c]{%
\begin{tabular}[#1]{@{}l@{}}#2\end{tabular}
%%%
}
\usepackage{float}
\begin{document}
\begin{table*}[htbp]
\scriptsize
\setcellgapes{3pt}
\makegapedcells
\caption{ABCD}
\begin{tabularx}{\linewidth}{|@{} p{1cm}| l| p{1.5cm}| p{3cm} |p{2cm}| X @{}|}
\hline
\thead{Paper}
& \thead{DNN}
& \thead{Train/Test}
& \thead{\specialcell{Performance} \\\ \specialcell{Measures}}
& \thead{\specialcell{Complexity} \\\ \specialcell{Runtime}}
& \thead{Critical Findings/Remarks} \\
\hline
\hline
\textbf{A} 2016 & A & A (PEIRVM)\footnote{https://groups.csail.mit.edu/vision/TinyImages}
& A
& \begin{itemize}
\item a
\item a
\end{itemize}
& \begin{itemize}
\item a
\item a
\item a
\end{itemize} \\
\hline
\textbf{A} 2019 & A & Camelyon 16\footnote{https://camelyon16.grand-challenge.org/}, Tupac
16\footnote{http://tupac.tue-image.nl/node/3}, Rectum
\footnote{https://www.pathologyoutlines.com/topic/colonhistology.html} & a & \begin{itemize}
\item a
\end{itemize} & \begin{itemize}
\item a
\item a
\end{itemize}\\
\hline
\textbf{A} 2020 & A &a & a & \begin{itemize}
item a
\item a
\end{itemize}
& \begin{itemize}
\item a
\item a
\item a\footnote{https://bellard.org/bpg/}
\end{itemize} \\
%%%% table body
\hline
\end{tabularx}
\end{table*}
\end{document}
Edit: My result of tests of the Zarko's solutions:
After second edit:
After third edit:
\specialcell
defined?\spacialcell
in not part of any package that you load in the preamble of your example code. If must be defined somewhere else. Does your original document contain something like\newcommand{\specialcell}...
?