On the other hand, for online banking that shows incorrect balances between the FI and QuickBooks, you can try to run a manual update on your bank account as an initial step. This way, you'll determine if there are bank transactions that were not downloaded in the Banking page.
In the left navigation bar, go to the Banking tab.
If you have other bank accounts connected, just check the box for the account you're trying to update.
Click the Update button.
If you're getting any error while doing the updates, follow some fixes listed in the following article below:
That information should allow your emails to send to your customers and also reconcile your FI and bank transactions. Please let me know how things go and if you have any questions by leaving a reply below. Wishing you a safe and wonderful week.