Function "Code_XL" does not exist

I'm trying to make a bunch of filters that look at the first letter of a surname.   In 10.5 the following worked:

Code_XL([Last Name])>64

.And.

Code_XL([Last Name])<68

If I try the same in 14.3 I get the validation message Function "Code_XL" does not exist even though I've picked the function from the menu on the filter screen.  Am I doing something wrong?

If I create a formula field to return the value using the same function that seems to work OK.  I guess I could make a filter based on that formula field but I'd like to know where I'm going wrong with the original filter as I'm going to need to replicate it in a large number of other models.