Hi,
I'm using {{customfield_xxx.diff(customfield_yyy).prettyPrint}} smart value in automation rule to display time in format: h, m,s (eg. 1h 2m 3s).
Rule is being executed successfully, Log action is capturing time in correct format, I have information work item has been updated:

but it's not, the field is empty:
Downtime CF is text field.
Automation rule:

Anyone know what it wrong?