Hi there, @Open_for_Business.

Thanks for getting back to this thread and providing further info.

Let me join in this thread and share additional steps to fix the issue. 

If you already followed the suggested steps shared above, I'd recommend doing a clean install in QuickBooks Desktop. This way, we can refresh the system and fix any ongoing issues within the program. 

First, uninstall QBDt by following these steps:

1. Open the Windows Start menu. Search for “Control Panel”, then open Control Panel.
2. Click Programs and Features or Uninstall a Program.
3. From the list of programs, select the version of QuickBooks Desktop you want to uninstall.
4. Click Uninstall/Change and then Remove.  
5. Select Next.  If you don’t see this option, sign out and sign back into Windows as an admin (or a user with admin rights).

When you’re done, reinstall QuickBooks Desktop.

If you're still getting the same result, contact our QBDT Phone Support. This way, they can perform further investigation and help you apply the customized templates. 

Moreover, you can check out= some of our helpful articles about managing invoice templates and fixing common issues when using and customizing templates:

• Use and customize form templates
• Fix common issues when you use and customize templates

I'm always around to help if you have more questions about managing your invoices or anything else related to QuickBooks. Take care and have a good one.