Prompt for user input not working with Simulink...

When I prompt for user input via a script that runs at the start of a Simulink model (the script is placed in the Callbacks>StartFcn directory), the input string (i.e. The prompt that is normally printed in the terminal) doesn't actually appear. You can still type the response and everything else will work, but the actual prompt is never displayed. Any ideas why?

Also, I've tried placing the script in the InitFcn directory too with the same results.