Hi officemanager-ti,

Welcome to Community!  Having the ability to update your transactions is a vital part of your daily bookkeeping tasks.  However, there are times when the connectivity between QuickBooks Online and various financial institutions is interrupted.  When this occurs, our Development Team will open an investigation to ensure the issue is resolved as soon as possible.  To see if your bank is currently linked to an investigation, I suggest contacting us outside of Community.  If there's an active investigation, our Customer Care team can add you to the list of affected users, and set you up for an email notification when the issue has been resolved. 

In the interim, you can manually upload your transactions following the step-by-step instructions in this article: https://intuit.me/3k1OofY.  To prevent duplicate entries when manually uploading your transactions, I suggest making note of the last transaction uploaded in your QuickBooks Online account by going to your Settings ⚙ > Chart of Accounts > Account History. If for any reason you find duplicate entries, the steps to remove them are also in the article provided above.

Schedule a Callback or start a Chat: click (?) Help in the upper right in QuickBooks Online > enter "Contact support" > hit Contact Us > provide a brief summary of your situation > hit Let's Talk > choose Get a callback or Start a Chat.
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If you have any other questions, please don't hesitate to reach back out.  We're always happy to help!