Hello teamchambie,

Let's perform some basic troubleshooting to determine what's causing the issue to happen when marking them as paid. You can start with running the Verify and Rebuild Data Utility to identify and self-resolve most data issues.

Here's how to Verify Data:

1. Click the Help tab at the top menu bar.
2. Click Utilities.
3. Click Verify Data.

To Rebuild:

1. Click the Help tab at the top menu bar.
2. Click Utilities.
3. Click Rebuild Data.

For additional information on this, please see the following article:

Verify and Rebuild Data in QuickBooks Desktop.

If the steps above don't work, you can try repairing the QuickBooks program this time. The steps are outlined in the screenshot I'm adding down below:

Please feel free to let me know how the troubleshooting goes. If you should have any questions, I'm just a click away.