Error while obtaining sizes from MEX S-function...need help please

Good evening,

I wrote a c++ mex function while using the template for a C++ example over here https://www.mathworks.com/help/simulink/sfg/s-function-examples.html#f6-61579. I made changes to the code inside the mdl wrappers, that I cannot disclose, but I was able to use the "mex" command to compile the code. Then came the fun part...

I wanted to create an s-function block in simulink that used the c++ mex function I defined, when I tried to run the s-function I got this error

Error while obtaining sizes from MEX S-function '..._cpp' in 'sfunc_.../S-Function'.
  Invalid MEX-file '..._cpp.mexa64': /usr/lib/libgdal.so.1: undefined symbol: _ZN11xercesc_3_111InputSource11setEncodingEPKt
  Component: Simulink | Category: Block error

So I thought at first it was a linking problem, which is when I found this solution https://www.mathworks.com/matlabcentral/newsreader/view_thread/336245 that told me to set a symbolic link to a library libproj.so.0, but that didnt work. I think the problem might be within how I defined my "mdlInitializeSizes" function within the mex file but I have no clues to where and why.

I am very new to using Mex functions, so I apologize if this is a simple answer. I have been scouring the Internet trying find a solution to this problem by looking at various Matlab Answer questions, and the best question that I thought would answer my question was in https://www.mathworks.com/matlabcentral/answers/194923-sumo-returns-error-using-system-command-on-a-linux-machine-while-it-works-properly-inside-termina. If anyone has any clues or thoughts please comment or leave an answer :).

Thanks