Hi, ashermasher.

This unexpected behavior can also be caused by a cache-related issue. When a browser's cache is full or corrupted, it can cause several issues within QuickBooks. One way to rule this out is to use an incognito or private browser: 

• Google Chrome: CTRL + Shift + N.
• Microsoft Edge: CTRL + Shift + N
• Mozilla Firefox: CTRL + Shift + P
• Safari (new versions): Command + Shift + N

Log it to your QuickBooks account, then check the accounts under the Banking tab. When they appear properly, go back to the regular browser and clear its cache. This will clear the webpage data that's causing the issue. 

Close out any browser instances to complete the process. 

Alternatively, you can use another supported browser to check your connected accounts. 

For more information, you can review this article as your future reference: Connect bank and credit card accounts to QuickBooks Online. In addition, you have the option to manually download your transactions in QuickBooks Online.

Don't hesitate to post again here if you have further concerns in connecting your bank account with QuickBooks. I'm always here to help. Keep safe.