I cannot get this to work in our environment and I've exhausted the ways in which I can express the problem into google.
The following is my test trigger to see what values I get from the smart value, which always resolves to 0
As can be seen in the following audit output

The automation has identified the correct parent Story, which has plentiful sub-tasks and original estimates.
The smart value used is mentioned in many threads regarding similar issues, often with a / 60, but since I was only interested in seeing any value, that has been omitted in the manual trigger.