This is probably because your bank changed the way they are syncing with QBO. Here is what you should try:

1. Make sure you can access your bank account via a log in ID and password on your bank website.

2. Disconnect the bank in QBO by going to the chart of account, edit account, click "disconnect and save."  Your bank account should be unconnected on your dashboard.

3. Click "connect" on the dashboard and follow the prompts.

4. If that does not work, contact your bank for more help.

5. If you manage to reconnect but not all the data appears since the last connection was in June, you may have to enter the data manually or use the "file upload" function.