I am trying to set a due date for all items in a checklist to be 1 less working day than the date in a custom field. This is the rule I've created:

The checklist loads, but it doesn't add the due date to the items. I've tried changing the number of working days in the formula, making the custom field one word, hyphenating the custom field, etc. What am I doing wrong?
*I'm referencing the "Arithmetic in Date Variables" Trello page.