Hi there, Brian228.

I'm here to help fix this template issue. You can have your client update their QuickBooks Desktop for Mac to the latest release. This is to ensure they'll always have our newest bug fixes and security patches. here's how to do it:

1. Open your QBDT for Mac
2. From the QuickBooks dropdown menu, select Check for QuickBooks Updates.
3. If a newer version is available, select Install Update.
4. When prompted, click Install and Relaunch.
5. Once the update is complete, QuickBooks for Mac automatically opens.

Once done, try creating or sending a sample invoice again. If the same thing happens, have your client to delete and recreate the problematic invoice template. For resources in managing your other sales transactions, you can browse a topic from our Help Articles page.

You can find me here if you have any other concerns or additional questions have a great rest of the day.