I can help you sort this out, @DJ33.

Let's first run the verify and rebuild utility tool to isolate this concern for possible data damage. Once completed, let's try to create a dummy estimate and convert it into an invoice using progress invoicing.

To run Verify Data utility: 

1. Select File menu.
2. Choose Utilities. 
3. Click Verify Data. 
4. If there are issues found, you’ll be prompted to Rebuild Now.  

Here’s how to run the Rebuild utility: 

1. Click the File menu.
2. Select Utilities from the drop-down option. 
3. Choose Rebuild Data. 
4. Click Ok on Rebuild has completed. 

Once completed, let's restart your computer to ensure that all components are updated. You can try creating an estimate and convert it into an invoice.

1. Create the estimate.
2. Click Create Invoice button.
3. Choose to Create an invoice for the entire estimate.
4. Review the details of the invoice.
5. Click Save and Close. 

To pay the invoice, here's how:

1. Open the invoice.
2. Click on Receive Payments.
3. In the Customer Payment window, review the payee information.
4. Put a check mark on the invoice that will paid.
5. Click on Save and Close. 

On the other hand, I've added these articles for more insights on the different available workflows to track your income and expenses in QuickBooks:

• Customer transaction workflows in QuickBooks Desktop
• Accounts Payable workflows in QuickBooks Desktop

Don't hesitate to get back to me if there's anything else you need while working with backups. I'm here to keep helping.