I can help clear things up to you, @wandellscottreal.
The 400 payment can be a duplicate transaction. It happens when you add it to the bank register and also have an existing transaction in QuickBooks at the same time. When you have recorded a payment transaction in QuickBooks, you can match it with an online banking transaction to avoid duplicate. For more details, you can reference this article: Categorize and match online bank transactions in QuickBooks Online.
Also, there may be an edited payment transaction or sales receipt and this entry resolve the difference causing the 400 payment to create a difference when clearing/reconciling the amount. If that's the case, you can review the Audit log for edited transactions by following these steps:
- Go to Gear and then select Audit log.
- Click the Filter button and then set:
User: All users
Date: select a period or custom date
Events: Show all events - Then hit Apply.

- Then select View when you see a transaction that's the same with 400 payment amount.

You can also check the Profit and Loss by Detail report to see a duplicate transaction on a given report period.
In case it's proven that the transaction is a duplicate, you can go to the bank or CC register to remove it.
Here's how:
- Go to the Gear icon and then select Chart of accounts.
- Find the bank in question.
- Click View register on the Action column.
- Select the payment transaction and choose Delete.

For additional insights, you may check out these articles:
If you have other questions in mind about reconciling accounts and managing transactions, please let me know so I can assist you. Have a wonderful ahead!