How to add a custom template to Word?

I’ve created a custom template, and I want to add it to the list of templates on the File>New page. I think I understand how it’s supposed to work, but it’s not working.

First, I’m not using Microsoft’s default folder for templates. I have my own system for saving application data that puts it all in one place where I can back it up easily.

I select File>Options>Add-Ins, select Manage: Templates, and click Go. Word opens a dialog that shows the name of the default template (Normal) and a list of other templates (currently empty).

I click Add, and Word opens an Open File dialog. The file is in the folder where I store Word configuration data with the filetype dotx. I navigate the dialog to that folder and select the file. The file’s name appears in the list of templates with a check mark next to it. The file’s full pathname is displayed below the list box, and is correct; that is, it points to the folder where the template is actually stored, not to Microsoft’s default. I close the dialog.

I return to the home page and click New. My custom template is listed along with the default template. I click it and get “Sorry, we couldn’t find your file.”

What is going wrong?