Try other browsers to see if you get the same issue.
If the steps given above doesn't work, I'd suggest contacting our technical support team for help. To further troubleshoot this issue requires an exchange of sensitive account information, while this is a public forum.
They can pull up your account in a secure environment and investigate this issue for you. Let me show you how:
Log in to your QuickBooks Online (QBO) account.
Click the Help button.
Click the Contact us button.
Whenever you're having problems downloading bank transactions and you need to update your bank feeds, you can import bank transactions using Excel CSV files. It's an article that shows you how you can manually upload your bank transactions to your QBO account.
Let me know if I can be of further assistance by leaving a comment below. I'll get back to you as soon as I can.