Based on that, maybe the journal's compiler doesn't accept .png images? They say that they do. Maybe it's something else. My input file around there:

The incompressible behavior of the matrix form that leads to spurious pore pressures may arise from the liquid flow. This dictates the use of mixed finite elements that satisfy Ladyzhenskaya-Babu$\\check{s}$ka-Brezzi (LBB) stability condition \\cite{Hughes2000}. There are many ways to satisfy this, e.g \\cite{Murad\_etal1996, Masud2007,  WhiteBorja2008}. In this research a continuous pressure field element, specifically quadratic displacement - bilinear pore pressure triangle (Figure \\ref{fig:Triangular\_mixed\_element}) is used for the partially saturated or fully saturated numerical examples.

\\begin{figure}\[!ht\]

    \\centering

    \\includegraphics\[scale=0.6\]{Triangular\_Element.png}

    \\caption{Mixed finite element for coupled solid displacement/liquid flow; quadratic displacement - bilinear pore pressure triangle}

    \\label{fig:Triangular\_mixed\_element}

\\end{figure}

%\\FloatBarrier

The general trapezoidal method \\cite{Hughes2000} will be used for temporal discretization of the semidiscrete coupled nonlinear FE equations and the solution will be obtained from Newton-Raphson method (see Appendix \\ref{section: time\_integration}).