Thanks for reaching out to us, userjasonlangton16.
Did you encounter any error when you try to connect it? That will help us in checking what's causing the issue. Here's how to fix Open Banking connection errors.
Also, make sure that Monzo Bank doesn't have any system issues. That can result in connection errors and prevent it from linking to QuickBooks Self-Employed.
In the meantime, you can manually import bank transactions. All we need is a file from Monzo Bank that we can upload to QuickBooks Self-Employed.
Keep your posts coming if you need more help. I'll be here!