As an initial troubleshooting step I recommend clearing the browser cache first. Doing so will remove anything that's keeping QuickBooks Online from updating with the new info from your bank. Here's how to get this done in Chrome for example:

1. At the top right, click More (three vertical dots).
2. Click More tools and then Clear browsing data.
3. At the top, choose a time range. To delete everything, select All time.
4. Check the boxes next to "Cookies and other site data" and "Cached images and files."
5. Click Clear data.

The following article provides similar steps for other browsers: Clear cache and cookies to fix issues when using QuickBooks Online. Once you've completed those steps, you can then log back into QBO and complete a manual update.

If the issue persists you may consider reaching out to the QuickBooks Online Support Team. Agents have tools that give them the ability to share your screen to take a more in depth look to determine what's causing the issue with the bank connection. They'll also be able to get this problem escalated for you if need be. The following article provides the steps to get in touch with the team: Contact QBO Support

Please feel free to reach back out if you have any other questions. I'll be here to help in any way that I can.