Why Am I Receiving Matlab.UI.Figure Errors

Hello Mathworks community,

I am quite new to MATLAB with regards to running anything more complex than a few matrix operations and signal processing functions. I am working on a piece of software that I believe was developed on an earlier version of MATLAB (R2012a). I am able to initialize the GUI (Figure - I believe it's called) but whenever I go to press a button to interact with the GUI, I am greeted with the "Error using matlab.ui.Figure/vertcat" error. I am wondering if this is due to version differences in the built-in Matlab libraries. Would anyone who is familiar with the matlab.ui.Figure package be able to tell me if there would be incompatibilities between MATLAB R2012a and MATLAB R2019b with regards to this specific functionality?

PS. I apologize if the question I am asking is trivial and/or a novice question. I know little to nothing about MATLAB's internals.

Thanks so much in advance!

[Geoff Hayes]

Sam - how are you launching the GUI? You mention "figure" so I'm just curious if this a GUI created with GUIDE (so there are .fig and .m files) and so if you launch the GUI via the .fig file, this will fail (you can launch the GUIDE GUI through the m file editor, the GUIDE editor, or from the command line using the name of the GUI). If this isn't the case, then please post the full error message to this question so that we can get an idea of what might be going on. Include any relevant code too.