Thanks for joining the thread, @franLBK.

There might be a data issue in your company file that's causing this behavior. This might be the reason why it's only allowing her to pay the returned check fee instead of the full amount.

Let's clear this out by updating QuickBooks Desktop to its latest release. Here's how:

1. Go to the Help menu and select Update QuickBooks Desktop.
2. Click the Update Now tab and select Get Updates to start the download.
3. When the download finishes, restart QuickBooks.
4. When prompted, accept the option to install the new release.

Once done, try sending the invoice again. If you're still getting the same result, run the Verify and Rebuild Data tools. These will help us identify the most commonly known data issues within a company file and fix it. 

If the issue persists, contact our phone support. They have the tools that could check your account and trace the cause of the problem. 

Here's how you can reach out to them: 

1. Go to the Help icon and select QuickBooks Desktop Help.
2. Click Contact Us.
3. Write your concerns in the description box, then select Continue.
4. Select which one of the support options you'd like to use.

Please check out our support hours to ensure that we address your concerns on time.

You can also run several reports to tell where your company stands. These offer critical information about your business and finances.

The Community always has your back, so please let me know if you have any other questions. I'll be more than happy to help. Keep safe.