There is a back-end issue where my credit card is now showing up as negative after losing sync. How can this be resolved?

This isn't the experience we want you to have, matthewrief . I'm here to make it up to you.

Before anything else, since you've mentioned that the issue is from the back end, I'd like to know the name of your Financial Institution, so we to check if there's an ongoing investigation into this matter.

Those were transmitted to QuickBooks by your financial institution, and QuickBooks doesn't have control over them. Constant security updates, connectivity issues, and data transmission interruptions are possible reasons behind the unusual behaviour of your transactions. 

It could also happen if you manually uploaded these transactions using a CSV file, and the file could be formatted incorrectly.

To get rid of this, we can exclude these transactions and then re-upload it again manually with the correct format mapping of the field before importing it and ensure to review the transactions before uploading to avoid duplicates. Let me guide you through the process.

Here's how to exclude transactions:

1. Go to the Banking page and select a Bank Account.
2. From the For Review tab.
3. Tick the checkbox of the transactions to exclude.
4. Then select Exclude.

You can refer to this article for more details: Exclude a bank transaction you downloaded into QuickBooks Online.

You can upload CSVs in either the following 3-column or 4-column format.

 If you use the Column 3 format, make the payment negative and then for the deposit without a negative sign. If you utilize the 4 Column format, put the payment under Credit and deposit under debit.

To learn more about how to check the correct format in importing your CSV file, you can refer to this article: Format CSV files in Excel to get bank transactions into QuickBooks.

I've also added the following article for future reference:

• Categorize and match online bank transactions in QuickBooks Online.
• Reconcile an account in QuickBooks Online

Let me know in the comment section if you have clarification or additional information. I'll be happy to guide you. Take care.