Your best bet is to just ignore all GUIDE CreateFcn() functions. Don't put any code into them. You can put code into the OpeningFcn, which executes once upon startup. Or you can put code into the OutputFcn() which executes once upon startup, after the OpeningFcn has run and after the FUI window has been made visible. OutputFcn also executes when the GUI shuts down. I really suggest you put lines like these into the functions to see when, and in what order, they are run:
fprintf('Now running OpeningFcn....\n');
Note, there are some lines of code that must be put into OutputFcn such as those to maximize the GUI window:
FigurejFrame = get(handle(gcf),'JavaFrame');
FigurejFrame.setMaximized(true);
