Remapping fields when using Googlesheets and a template that needs modifying

I used the “Employee Directory” template and Googlesheets to make a simple directory- I wanted to change some of the fields- but when i did that it lost the mapping, and i cant see how to “remap” to the columns i want displaying?- so nothing displays Is there a way to do that or do i need to start from scratch with a new app and new list. Thanks

Just to confirm, when you click on the dropdown : Map to, you see no fields to add after it lost its mapping? And have you by any chance changed the name of the googlesheets file itself?