Thank you for posting back and sharing a screenshot, @HollyJ.

I appreciate all the steps you've performed to resolve the payment differences, and I want to make sure this is taken care of.

At this time, I suggest reaching out to our QuickBooks Support Team so they can investigate why you're still receiving the error even though the difference is already $0 and provide additional troubleshooting steps to get this fix. They can also create an investigation ticket if other users are experiencing the same.

To reach them, click the ? Help button at the top right corner of your QuickBooks Online and select Contact Us to talk or chat with a live agent.

Just in case you want to learn more about matching transactions, feel free to check out this article for more guidance: Categorize and match online bank transactions in QuickBooks Online.

Please touch base with me here for all of your QuickBooks needs, I'm always happy to help.