I am trying to configure an automation for triggering a field value update for a 'Number' type field based on difference between 'Start date' and 'Due date' (both built in date fields) whenever any of these fields is updated/changed. Need is to have the duration (in days) between these two dates filled up in the 'Number' field.
Automation put in place is

I configured a smart value for Edit issue fields in the following manner to achieve what I wanted

When the automation is executed, the automation log shows success. Here's the screenshot

However I am not getting the desired result i.e number of days is not getting populated in the 'Number' field 'Duration'
