Welcome to the Community, @Jodi_Smith.
Allow me to help share information about reconciling transactions in QuickBooks Online (QBO).
The missing charge in the register may not have been added or entered into QBO. You may need to verify the transactions manually and add the missing ones and ensure that the date is correct.
Also, I've added this article that can guide you on how to reconcile accounts in QuickBooks Online.
Don't hesitate to get back in here if you have other queries. I'll be here to help you out. Keep safe!