Hello Andrew.
The short answer is: Yes.

I did a number of things.
I initially had long file names, and things were not working.
So, I renamed them so that each file name is either 7 or 8 characters.
As well, I entered the values into the first customer, and then I exported the field values.
In Excel, I simply copied the values to all the rows.
But when I import the file, the fields remain blank, and the first customer that originally had values, now appears blank in these fields.

It just is not working for me.