Checking the ‘do not run on each row’ box doesn’t actually do what you would expect. Instead of running the merge syntax in a row context for just the first row, it processes the merge syntax in a model context.
As a workaround, you can uncheck the box and use global merge syntax to get just the row you want.
All I had to do was uncheck the ‘do not run on each row’ and it worked. The context merge syntax should work in either situation imho.