Welcome to the Community. It's essential to connect your bank to QuickBooks Online to keep your books up to date. I'd be glad to point in the right direction to get the support you need.
This type of issue can be caused by browser cache and cookies as they can prevent the system from functioning effectively. I encourage you to refer to the following steps to complete some browser troubleshootings.
If the steps provided above don't work, I recommend that you contact our customer support team. They'll be able to take a closer look at your account regarding two-factor authentication. Here are some options available to reach out to our team.
Phone: Call us at 1-855-253-1536 from Monday to Friday between the hours of 9 AM and 8 PM EST.
Schedule a Callback or start a Chat: click (?)Help in the upper right > type and enter "Contact support" into the QB Assistant > click Contact Us > explain your situation > click Let's Talk > choose Get a callback or Start a Chat.