Welcome to the Community. Let me help you connect your bank account in QuickBooks Self-Employed.
You can perform some basic troubleshooting to ensure it'll connect to the right account. Please try searching your bank in QuickBooks using the business account URL.
Also, can you share with us the bank you're trying to connect to QuickBooks? This way, we'll be able to check for any reports similar to what you encounter on your end.
I've attached an article you can use to upload bank data manually in QuickBooks: Manually import transactions into QuickBooks Self-Employed.
Keep us posted if you need anything else regarding the setup. Have a great day.