Can't Run My Processes With RedirectStandardOutput = True

I have a command line application given to me by a partner of my company. I built a simple interface to automate the process. I use it to run various different actions. All I'm doing is launching the process and hiding the window.

To test my app, I just ran each task and updated the UI with a "pass" each time. But really, I need to update the UI with a "pass" or "fail" based on the results that the CLI provides.

Since the CLI itself doesn't produce a log file, I decided to redirect standard output. That works great, except the application stops working.

When I run a specific task without redirecting, it takes about 5 minutes to complete. When I do it with redirecting, it completes instantaneous and the output says the test failed.

So redirecting isn't even allowing the CLI to run correctly.

Has anyone come across this issue before?

Thanks